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Animation Module Overview Most parameters in Shape can be animated over time. This can be used to generate time variation of the models either for scientific modeling of time varying phenomena or for visualization purposes. A simple example application is the simulation of the lightcurve of an exoplanet or of eclipsing binary stars. An application that aims more at purely visualization could be rotating the virtual camera around an object go generate a movie that shows the structure as seen from many points of view. Since animation implies the generation of a large number of individual images that can be joined together in the Movie Module, care needs to be taken in preparation in order for the rendering process to not take an unacceptably large amount of time. The key question is which type of rendering do you need : Camera motion: If you animation will consist of camera motion only and the spatial resolution that you need is small enough to allow you to use the grid renderer, then you can save a lot of time. In this case the steps before the final ray casting to determine the image pixel values can then be precalculated and saved. Then they do not need to be repeated for every frame. Another option to get a camera animation is to use the interactive iluvia software from ilumbra.com . Using the Export Module in Shape you can quickly output your model in a format suitable for iluvia and inspect your model interactively or very quickly set up and capture animations. Varying model parameters: If parameters of the model itself need to be changed over time, then the precomputed grid changes and a full render is needed for every frame. For complex models and high resolutions, this may take a lot of time to compute, depending on your computing equipment. Once you decided which type of animation and spatial resolution you need, you can time the rendering and estimate the total time it will take to render the necessary number of frames. For each rendering, come basic stats are output in the Info Module that include the time it took to render. This information can be used to estimate the total time necessary to render out the full animation. General workflow: 1. Set up the timing and output parameters in the Parameters Panel on the right. 2. Select variables to be animated from the Parameter Tree. They appear in the Animation Parameter Stack. 3. Select each animated parameter in the Animation Parameter Stack and set up its animation graph as a function of time 4. Render the animation Animation Module UI: The Animation Module is divided into five main sections. A control bar is at the top and the parameter tree and the animation parameter stack are on the left. In the middle you find the animation graph for the animated parameters. At the bottom is the time line . Finally, the General and Output parameters are in the panels on the right. Control Bar: Animate: Starts the rendering of an animation. After each rendered image it advances one frame and renders again. Refresh: Updates the Parameter Tree after new renderable parameters have been added somewhere in Shape. This does not happen automatically, so make sure to click on this button to see any new parameters. Up & Down: In the Animation Parameter Stack move selected parameters up or down. This has no effect on the result but is helpful to keep order in the stack when a large number of parameters is animated. Remove: Removes selected parameters from the Animation Parameter Stack. Copy & Paste: Copy the animation graph from a selected animation variable in the Animation Variable Stack and paste it to another that you select after copying the previously selected graph. Parameter Tree: The parameter tree is a hierarchical list of all animatable parameters. The parameters may be from the UI, general project parameters or from particular objects. Additionally global parameters that have been defined in the Math module will also show at the bottom of the parameter tree. To select a parameter for animation, open the parent branches in which it is located. Once the parameter appears, double click on the tick box to the left of the parameter name. When the tick mark is on, the parameter appears in the Animated Parameter Stack, where the time variation of the parameter is set up (see below). Note that newly created parameters or objects do not automatically show in the parameter tree. To have them appear click on the Refresh button in the menu bar at the top of the Animation Module. Animated Parameter Stack: The Animated Parameter Stack is the list of parameters that are selected from the Parameter Tree to be changed, i.e. animated over time. The first column shows the Parent branch in the Parameter Tree, the second is the name of the parameter. The third column contains the value of the parameter at the current time of the animation time line. To select a parameter click on the row for that parameter. Automatically its animation graph will be shown. Animation Graph (not shown): In the Animation Graph you set up how the parameter selected in the Animation Parameter Stack changes over time. Note that in this graph the x axis is in units of time as defined in the Parameter Panel on the right (see below), whereas the Time Line at the bottom is in terms of the frame number. The graph is not shown here . It work the same way as other graphs in Shape. For more information on how to set up a graph see the manual page on Graphs . Parameter Panel (right side) General: Timing and frame numbers are set up in this tab. Name: The base name of for the output frames of the animation Start Frame: The frame number at which to beginn the animation. It may be necessary to start from a position different from 0 or 1 when an animation was interrupted or if several will be concatenated. # Frames: The total number of frames for the duration of the animation from the Start Time to the End Time . Start Time & End Time: in terms of time units (see below) when is the animation meant to start and end. Time Units: Select the desired time unit from the drop-down list. The default is Years. Make sure the unit in the Variable tab is the same or consistent with the needs for this model. The animated variable that is selected and displayed in the graph uses the units from the Variable tab . Occasionally these units need to be different from each other. Fields: Include the calculation of field lines, magnetic or velocity. Distribute: Recompute the distribution of particles for each frame. Render: Do a full render at each time step. Camera animation with "Autorender" on in the Render Module does not require this, since the model grid does not change and is calculated either before the animation is started or with the first frame. After that autorender is used if the Render flag in the Animation Module is off. Variable Some control parameters for the animated paramater that is currently selected in the Animated Parameters Stack . Time Units: The time units to be used for this variable. Make sure it is the same as the Time Unit in the General tab or you are certain of the animation graph in this context of a different general time unit. Enabled: Enable the animation of this variable. If for some reason you disabled this variable, then later you might wonder why it doesn´t change in an animation. It may well be that you forgot that you disabled it. So, if something in your animation doesn´t change as expected, make sure all the variables that you need change are actually enabled for animation. Stamp: The total number of frames for the duration of the animation from the Start Time to the End Time . Stamp Format: The number format for the numerical stamp. Output: Here you define the output format and what you wish to output and where on disk it is to be placed. Directory: Set the output directory for the individual animation frames. Note that the name of the files is set in the General Tab. Image Type: Specify the image type by writing the standard extension for the image. For instance, if you wish to output PNG format images, then write ".png". 3D Mesh: Output and image of the 3D Mesh. Note that it is not the mesh itself that is output, but rather an image of the view in the 3-D Module. Hydro: Output the full data from the hydrodynamics module at each time step. Note that, depending on the resolution, this might lead to a large amount of data to be output. Plots (Images): Output images of any graphs that the animation might generate in the Graph Module. You can adjust the image resolution for these outputs. Plots (Ascii): Output the ASCII values of any graphs that the animation might generate in the Graph Module. Math Variable: Output any math variables that change over time during the animation. Stereo: Output stereo images. dStereo (deg): The parallax anglee. This is the difference between the horizontal camera angles for the two stereo images.

Modifiers The Image Displacement Modifier uses an grey-scale image to move vertices as a function of the image pixel intensity. This allows one to use actual images to influence the model structure. As shown in the example mesh on the right, a potential application is in the modelling of spiral galaxies. An external drawing device can be used to design structures almost interactively with the automatic update functionality. For this example the image of a spiral galaxy was smoothed and a flipped copy of it generated. The flipped version is needed for the top-bottom symmetry of the galaxy structure. The image on the right is the rendered image. The Image Displacement Modifier (IDM) works in a similar way as the Bump Modifier with the basic difference of using an image as data source instead of a simple function. The handling of the Gizmo for placement is similar. One difference is that the Gizmo of the IDM include a preview of the image to help with the precise placement and scaling. In this example of a spiral galaxy two IDM are required, one for each side, as shown in the example modifier stack on the right. Parameters: Name: If multiple Modifiers are used, make sure to name them adequately for ease of identification. Enabled: When deselected, the modifier will not be applied. Filename: Click on the button on the right to open the file selection dialog to open the image file to be used to the IDM. The filename will be displayed in the text field. Width & Height: The full size of the image in the 3-D Module in local x & y directions. Radial: Select this option if you wish the displacement to be radial from the origin of the Local Coordinate System of the mesh. Auto Update: If you change the image texture using an external software such as Gimp or Photoshop, then you can enable the automatic loading of the image by clicking on Start. Make sure to Stop it again after you finish. Since the image is read from disk, you need to save it after every change you want to be updated in Shape. Interval (ms): The the interval between Updates of the image from disk. Magnitude: Set up the how the mesh displacement shall be as a function of the pixel brightness of the image assuming that it has an interval from x=(0-1) for greyscale values of (0-255). You can use an analytic function of x (the pixel value between 0 and 1) or a corresponding point function. Widget: Opens the Widget panel shown on the right and enables the preview of the displacement image that helps to place it correctly. To see the preview image, the Display has to be enabled and the object needs to be selected in the object tree. The not only the Widget arrows are show, but also the preview image as shown below the Widget panel on the right. Note on Rendering IDM objects: Below are a few renderings of the example galaxy object. The first one shows the rendering at an intermediate viewing of the disk. At the center the bulge is seen as a vertical uniformly lit structure. This is typical for the applications of the IDM, especially with small-scale features. These turn out to look like little vertical "sticks". There are a number of measures that one can take to remedy that depending on the feature and the application of the IDM. For the smooth structure of the galaxy, for instance, one can use the Taper Modifier to taper off the emission towards the surface of the mesh. This is shown below where the galaxy has been rendered edge-on. The upper image is without and the lower one has a Taper Modifier applied. In addition to the IDM to strengthen the spiral features in the galaxy an Image Texture Modifier was applied with the same image. Modifiers: Image Displacement

The Shear Modifier changes the distance of the mesh vertices perpendicular to a chosen axis (default: local z-axis) along another axis. The orientation of the shear axis and direction of the shear can be changed by changing the values in the Axis boxes. Choose a value of 1.0 to select a particular axis (setting the others to 0.0). Intermediate value result in an intermediate axis. A better way to set the reference axis is using the Widget. The Magnitude dialog allows you to define the squeeze amount as an Analytic Function of position along the reference axis. You can also use a Point graph where you can generate an arbitrary function by manually placing points and setting the spline interpolation. To do this, select Point from the Function drop-down list under the graph. The example graph on the right shows the way it was done for the example mesh displayed below. Modifiers: Shear

The Squeeze Modifier changes the radius of a mesh perpendicular to a chosen axis (default: local z-axis), The action is similar to squeezing a soft object or to that of a lathe. There are three different Modes: Scale, Inverse Scale and Absolute . In the Scale mode the distance of the mesh points from the reference axis is scaled by the factor given in the the Magnitude graph as a function of position along the reference axis. In the Inverse Scale mode the scaling factor from the Magnitude graph is inverted. In the Absolute mode the mesh vertex is placed at the absolute distance provided by the Magnitude graph. The Magnitude dialog allows you to define the squeeze amount as an Analytic Function of position along the reference axis. You can also use a Point graph where you can generate an arbitrary function by manually placing points and setting the spline interpolation. To do this, select Point from the Function drop-down list under the graph. The example graph on the right shows the way it was done for the example mesh displayed below. Modifiers: Squeeze

Key Sub-S ystem: The Modifier Stack A model in Shape is build starting from a few basic mesh objects such as spheres, cylinders, tori or imported ones. Very few objects have such regular structure, however, and the fundamental purpose of Shape is to enable the user to reproduce any structure the universe comes up with at us as closely as possible. There these "primitives" have to be "modified". That is why the operators in Shape are called modifiers . Since there is a large variety of modifiers, the are assembled in a modifier stack (see the image on the right). This list of modifiers operates on the primitive mesh in sequence from the top to bottom. It is very important to note that for some operator combinations, such as rotations, the order in which they are applied makes a difference. When a new modifier is added from the drop-down list that opens by clicking on the plus (+) sign below the stack, it is added to the bottom of the list. They can be reordered by dragging and dropping them into the desired position. To delete one or more modifiers select them in the stack and then click on the "x" at the bottom of the stack. For good practice we recommend to order the modifiers by type as long as the order can be chosen without affecting the result. Modifier that apply to physical quantities such as density and temperature should go at the top, as shown in the example. Copy-Paste modifiers: Modifiers can be copied within the same stack or to the stack of a different object. To copy the modifier to the buffer click on the Copy icon at the bottom of the stack. Then click on the paste button right beside to paste it to the same object. To paste the modifier to a different object, select the target object and click on the paste button. When you do that, a small pop-up window opens with two option to select from. You can paste the modifier as a "new copy " or as an "instance ". The new copy of the modifier will act independently of the original. The instance of the original will work in unison with the original. This means that changes in the parameters of one instance will be automatically transferred to the other. You can have several instanced copies of the same modifier, thereby saving time by changing only one of them to affect all the others in the same way. This is an easy way to maintain the same structure for several meshes or other features of an object. Modifiers: There are basically three categories of modifiers: physical, geometry and transform . In the modifier stack these are identified by having a green, orange and white background respectively. The physical modifiers act on the local physical properties that determined the interaction of the gas with the radiation. Examples are the density, temperature, velocity or boost and points . The geometry modifiers move the vertices of the mesh to turn the primitive starter shapes into more complex structures. Examples for these are the bump, squeeze, twist and size modifiers. These modifiers do not move the origin of the local coordinate system. Contrary to the geometry modifiers, the transform modifiers precisely do move the local coordinate center . The physical and geometry modifiers then take the new local coordinate center as a reference. Links to descriptions of each modifier can be found in the Index .

Render Module Properties Panel: Units Properties Panel: Units Observational astronomers and theorists often work with very different units. This can be accommodated for in Shape by choosing the units that work best with your reference images or target audience. World & Image units: Various units can be selected for the World (Coordinate System) in the 3-D environment and the Images. The appropriate unit is selected from a drop-down menu and by default is set to meters (m). Some of the units are in terms of typical linear and others are in angular sizes. Energy: The energy units refer to the intensity units of the images. In addition to the SI (International System) some of the typical astronomical units are also available. Distance: The units for distances are similar to those for the World & Images, except that the angular units are, of course, not available.

The Stretch Modifier changes the mesh vertices along a chosen axis (default: local z-axis) as a function of distance from the axis. There are two different Modes: Scale and Absolute . When you switch on Absolute, the values in the Magnitude graph are the distance from the axis in units of the current project instead of a scaling factor based on the original shape of the mesh. The Magnitude dialog allows you to define the stretch amount as an Analytic Function of position along the reference axis. You can also use a Point graph where you can generate an arbitrary function by manually placing points and setting the spline interpolation. To do this, select Point from the Function drop-down list under the graph. The example graph on the lower right shows the way it was done for the example mesh displayed below. It scales a spherical primitive mesh to a disk with a hump around a certain distance. This modifier is ideal to set up a disk with a complex structure. Modifiers: Stretch

Maps Module Overview Channel maps are spectroscopic images, where the image contains only emission from a certain small range of wavelength or line-of-sight velocity. They are typical for spectroscopic radio observations, but have come into more frequent use also in the optical and infrared spectral ranges. Usually they are presented in an array of many channel maps representing the complete spectral range that has been observed. The full set of spectral data is often referred to as a data cube, since the image can be arranged as slices of a cube. The Maps Module is divided in three main sections. The dominant region is the display of the channel maps. Above the maps is the main menu and to the right are the parameter tabs. There are three tabs for General parameters, those for an individual selected Channel and for the Output of the channel images (maps). General Workflow: In the General Parameters tab the minimum (initial) and maximum (final) velocities are applied. These are then divided in a number of channels that is the product of the number of channels in rows and columns. To set up this grid of channel maps click on the "Re-grid" button in the main menu and confirm. This generates the grid of image windows. Now render by clicking on the Render Button in the Render Module or press Ctrl-S. Parameter Panels: General: Render: This flag controls whether the channel maps are rendered at all. Make sure to have the tick mark set when using the Map Module. Initial vel: The smallest velocity to be included (can be negative). This is the center velocity of the first channel map (top left in the grid). Final vel: The highest velocity to be included. This is the center velocity of the last channel map (bottom right in the grid). Delta (D) : This is the width of the velocity channels. If set to zero, then the width is calculated from the difference between the final and initial velocity divided by the number of channels. If set manually, then the channels may be narrower than that or wider, in which case they overlap. The intensity taken into account is constant over the interval, which may or may no be the case for the actual observations. Rows & Columns: The number of rows and columns that the channel map grid shall have. The total number of channels is then the product of rows and columns. Transparency: The transparency of the rendered foreground image. It can be changed with the slider to transition between rendered and observed background image. This helps to compare the model with observations. Light Echo: This function is deprecated. Difference: Show the difference image subtracting the observed image from the rendered model image. Export: Export the rendered image in ASCII format for further external processing. Channel: Select a particular channel by clicking on the image in the grid view of the channel maps. The selected channel is highlighted by a thin red line. The Channel parameter panel on the right then displays the settings of that particular channel. To view the image of this channel by itself at a larger scale, click on the "Expand" icon in the main menu of the Map Module. Vel (km/s): The velocity center of this channel. D vel (km/s): The full width of the velocity channel. Image: A reference or observed image can be loaded to be compared with the observation. One can transition between the rendered model and the reference image by changing the Transparency in a numerical way (see below) or using the Transparency slider in the General parameter panel (see above). The reference image can be placed and processed using similar attributes as those used in the Selected Window section of the Render Module. Please see the pages on "Data Preparation " and the Render Module for more details on how to use the Location parameters and the image Modifiers. Output: The output parameters control the appearance and labeling of the grid image output using the Save Grid or Save Images button in the Main Menu of the Map Module. An example grid output is shown on the right. CrossHairs: Mark the center of each channel with a cross. Labels: Label each channel with its central velocity. Color: The color for the labels. Change the color by clicking on the colored squared. A dialog opens to let you select a different color. Menu bar: Re-grid: After you adjusted the General Parameters for the grid of channel maps, the Re-grid button sets up the grid using these parameters. When you change the General Parameters use this button again to apply these parameters. Insert: Individual channels can be inserted before the currently selected channel. Note that this channel does not change the parameters of the pre-existing channel and is therefore not part of the regular sequence that was established using the Re-grid button. This new channel needs to be set up individually in the Channel parameter panel. Delete: Delete the currently selected channel. Save grid & Save images: save the grid of image or individual channel images. Se the section on Output above for details. Palette: Opens the image adjustment dialog for the channel maps. Here you can adjust brightness, scaling, and add other image modifiers. Note that the Gaussian Blur modifier handles the resolution of the maps. This is currently disconnected from the Seeing parameter in the Render Module and needs to be adjusted separately. In the Maps Module it works in terms of pixels, so it is depends on the resolution. This feature will be improved in a future release. Properties: Opens the Properties dialog for the detailed appearance of the grid coordinates, tick marks, fonts and colors. Load obs: Load observed or reference images to the background of the grid. Here you can load a sequence of multiple images to fill all the channels. Select multiple image in the directory dialog that opens by clicking on the first of the sequence and then Shift-click on the last. Reference images for individual channels can be loaded or changed with the corresponding Image load button in the Channel properties panel. Expand: Expands the selected individual channel image to full size of the image grid area for a detailed view. Clicking the same button again restores the full grid.

Filters for physical quantities in Shape can be defined here. Movie Module Overview In the Movie Module you concatenate individual animation frames into a movie. It can be reproduced in the integrated movie player and saved to disk for viewing in an external movie player. Several movie can be displayed side by side. These can then be saved into a single movie file. This is useful when comparing different visualizations of the same object simultaneously. Menu Bar: Create: Once you loaded the animation sequence of images, click on the Create Button to render the movie in a single file for viewing in external movie players. Add: Add a second or more movie panel to the right of the current one. Several frames can be rendered side by side into a single movie. Delete: Remove the currently selected movie panel. Select by clicking on the panel with the left mouse-button. Load: Load a sequence of animation frame into the currently selected movie panel. When you click on the Load button, a file dialog open. Select the first of the frames. Then go to the last one of the sequence and Shift-Left-Click it to select all the frames from the first to the last. Click "Open" to load them into the frame buffer of the selected movie panel. Options: Name: Set a descriptive name for the filter. This name appears in the Filter selection drop-down list in objects in the 3-D Module. Enable: The check box activates or disactivates this filter for all objects that use it. Mode: Here to can chose the Mode of the filter, which refers to whether the range between the Min and Max values is to be included or excluded. Clamp: If checked then all values above the Max values are set to the Max values. If unchecked, then the value is set to zero. Min & Max: The minimum and maximum of the filter range.

Render Module Overview This module takes care of the rendering of image and position-velocity diagrams. The output of 3-D volume data is also controlled from here. Overall the Render module consist of the render area where images and position-velocity (P-V) diagrams are displayed on the left side. On the right side you have the render Properties panel . It can be hidden by clicking on the Properties pane on the right. By default the General rendering parameter panel is open. From the drop-down list at the top of the panel several other sub-panels can be opened that deal with the settings for the virtual Camera , the Spectrum , the 3-D Output , Units and those of the Selected Window . We will deal with each of these in their respective sections below. In the default configuration only one image is rendered. If more images and P-V diagrams are to be show, those can be added and configured in the Windows drop-down menu above the render window. In the example above two columns have been set and three P-V windows have been added to the default image window. The slits for each P-V window is represented on the image window. In order to delete a window click on the X icon in the top-right corner of the window. Note that this icon may be hidden if the overall Shape interface has been reduced in size. If so, then resize the user interface until the X icon appears and then click to delete the corresponding window. The Image Render Window As the name suggests the Image Render Window displays the output images from the rendered model. To keep order when you have several windows, they can be named individuall y to remind you of the expected content. Just replace the text "Window 1", etc., in the text field of the menu above the window. In the same window several types of images can be displayed by selecting one of the five colorful icons above the image. By hovering over an icon a tool-tip gives a brief hint to what the corresponding image displays. By default a grey-scale image is displayed that represents the brightness variations that have been integrated along the line of sight. The selected type of image is marked by a blue border around the icon. The "Color Image" displays the each sub-object with the color that was assigned to its mesh in the 3-D Module. This allows to clearly distinguish and identify them for diagnostic or visualization purposes. Importantly, in the P-V diagrams it helps distinguishing the contributions by different parts of the model. The "Red/blue Image" displays the model in terms of its red and blue shifted regions. Volume cells with a velocity vector that points more towards the observer is colored blue and those with a line of sight component that points away are red. Regions were line-of-sight integration has a mixture of red and blue contributions will appear in a mixed color tending towards white. The "Rainbow Image" is similar to the red/blue image in that it color codes the velocity field along the line of sight. The difference is that a continuous color coding is used that follows the spectral rainbow colors. The range of velocities to be color coded can be set up in a right-click menu. The "Spectrum Image" uses the physical spectrum as set up in the Spectrum section of the Properties Panel on the right of the Render Module. Again the color coding follows the rainbow colors that are distributed through the range of the physical spectrum. Now the rendered color will depend on the full physical setup of the model. Therefore this image type is used to render physical and photo-realistic models. The "Image Modifiers" handles the operators (modifiers) that process the rendered image in terms of brightness scaling, contours, inversion, etc. The "Move Slit" icon activates the interactive changing of the slit parameters such as position and width. When active the slit width is change using the mouse wheel. The horizontal position is changed by pressing and dragging the left mouse button. Vertical size and position are change the same way while keeping the "y" key pressed during the operation. The "Zoom Image" button activates zooming in and out of the image using the mouse wheel. The "Pan Image" button activates moving the image left, right, up and down by dragging it with the left mouse button pressed. The "Render Window" button allows you to drag out with the left mouse button a rectangular window on the image. Combined with the HD renderer and the "Use window" option in the General tab of the Render Module only this region will be rendered. This can greatly reduce rendering times if you need high resolution, but only need to see a small region for testing. The "Image Transparency" button allows you to change the transparency of the rendered image to be able to compare with the background reference image. Close and Remove the Window by clicking on this button and confirm in the pop-up window. Properties Panel The Properties Panel on the right side of the Render Module has several section that can be accessed from the drop-down menu at the top. We will deal with each of them in the order they appear in the menu. General The general project properties are set up in this panel, such as spatial resolution, type of renderer, memory management, autorender, etc. Camera Camera orientation angles are set. The parameters include position angle, inclination, and angles with respect to the axes of the global coordinate system Spectrum The spectral range for the physical radiation calculations is provided here in various possible units. Output Ouput of the full 3-D cube to file in different forms. Selected Window Key parameters of the currently selected image or P-V window can be set in this panel. General Camera Spectrum Output Selected Window

Render Module Properties Panel: Spectrum Properties Panel: Spectrum Shape calculates the physical radiation properties over a user-supplied range of wavelengths. By default this range is given in terms of velocity (km/s) from a reference wavelength (5e-7 m). This allows a straightforward calculation of position-velocity (P-V) diagrams from a default setup. These defaults can be changed to a range in terms of wavelength in meters (m) that typically ranges from 3.5e-7 to 7e-7 m for the optical spectrum. For the modeling of radio observations the spectral unit can be set to Hertz (hz). Min & Max: The start and end of the spectral interval. Lambda_0 (l_0 ): The reference wavelength (rest wavelength) for the calculation of red- and blue-shifts in terms of velocity. # Bands: The number of spectral bands to be computed. The spectral range is divided in this number of sections of uniform width. If the shape of the spectrum is important or spectral line structure is meant to be computed, this number is set between 20 and 100 or so. When the overall color of an image rendering is all that is needed, then between 5 and 10 bands is usually sufficient.

Render Module Properties Panel: Camera Properties Panel: Camera The Camera parameters include various rotation angles in different coordinate systems. The are either observer oriented, such as position angle (PA) or inclination. Or, they are rotations around the Cartesian world coordinate axes. One can change from Orthogonal camera projection (on by default) to perspective camera. Furthermore various filters or "modifiers" can be applied to the data prior to the final render or after the render. These modifiers are discussed in more details below. Scene size: The width of the computing domain in terms of physical units, which by default is meters (m). This number corresponds to half the voxel size assigned to the Resolution parameter above. The physical domain runs from -(scene size):+(scene size). Scene center: The center of the cubic computational domain may be shifted in the physical scene that might be larger than the rendering domain. Setting a smaller domain with a shifted center may be useful for testing purposes or for achieving higher resolution outputs for certain regions. HD: The high-definition (HD) render is activated with this flag. It does not use a predefined cubic voxel grid and works similar to a ray-tracing engine that integrates to the pixel plane. If there are computations that depend on light sources, such as dust scattering, it is computed along the way. This may require more time, but is much less memory intensive. Therefore higher resolutions can be achieved. Fast renders, e.g. for camera animation movies, is not possible, however, since the some information is not stored for quick rendering from the precomputed voxel grid. Scatter Grid Size: When the HD render mode is switched on and scattering or photo-ionization processes are to be calculated, a sub-grid needs to be set that comfortably fits into RAM, but is as large as practical to avoid potential artifacts at grid limits. Recommendable is about half of the size that you can fit, if HD is off. Save grid: The grid data used for the final render step are retained in memory. This allows the Autorender (see below) to work. It requires more memory though and hence limit the achievable resolution smaller than with this option off. So, if you are doing quick tests or plan on rendering camera animations, then this option is convenient to be on. Auto render: If the HD is off or the Save grid flag is on, then data of the full grid have been saved and can be used to quickly render the scene for different camera views and animations. When you change the parameters of the camera the rendering updates automatically. The effect is not "real time" and may take a few seconds, depending on the resolution. Use window: For quick render in HD mode that require only a small portion of the image to be rendered, you can set a window using the Window Button above the image. Click on the icon with the square and then drag out a rectangle with the left mouse-button pressed. If the Use window flag is on, only this region will be rendered. This reduces the rendering times during model development when it is sufficient to see only part of the model. Overlay: Occasionally it is convenient to retain the previous image or images and add progressive images together. This is useful for diagnostics or simply as a nice "special effect.

Overview For many astronomical objects spatially resolved observations of the velocity structure are a key constraint to find their 3-D structure. Therefore it is essential to have a way to model the velocity structure of an objects in Shape. This is provided in the form of a Velocity Modifier that can be assigned to any geometric object . Since velocity is a vector , the velocity modifier is probably the most complex modifier and, in some aspects, conceptually different from scalar modifiers such as the density modifier. The main control panel of the velocity modifier is similar to other modifiers exposing the f0 scaling factor that is also incorporated in the Magnitude graph. The main difference to other modifiers lies in this Magnitude graph , which we are going to discuss in some detail. Similar to other modifiers there is the set of graphs on the right and the options on the left. We will therefore focus on the drop-down lists on the left side for the General options, the types of Vector Field and the Dependencies. General: The general options are again similar to other modifiers where you can choose as modes Custom and Analytic, as well as the type of coordinate system (Cartesian, Spherical, Cylindrical). Here you can also set the f0 scalar factor that multiplies the final vector. f0 is also exposed at the higher level main panel for the velocity modifier. Vector Field: This is one of the two key differences compared to other, scaler modifiers. This drop-down list allows you to choose from a variety of predetermined vector fields , including Radial, Disk Rotation, Elliptical, Collimated, Random, Custom, and Path . The practical importance of these options is that all except the Custom field preset the direction of the velocity vectors in space. For these one only needs to set the magnitude as a function of position using the graphs on the right. For these fields the graphs on the right work the same as in other modifiers yielding the scalar magnitude of the velocity vector . Except for the case of the Custom field the coordinate tabs do not represent the velocity components! The Custom field is described below. There is however an important difference. By default it is the same function, separable in their coordinate directions, as for other modifiers. In the velocity modifier it is, however, possible to choose on which spatial variable (u,v,w) each of the vector components (vu, vv, vw) depend on. Here (u,v,w) corresponds to the coordinates in the different types of coordinate systems. In Cartesian coordinates, for instance, the vx component may be defined as a function of the y-coordinate. It is important to note, however, that the actual variable in the analytic expression always x. What changes is its meaning according to the options that have been chosen. This allows to set up quite complex velocity fields. Additional complexity can be obtained by adding several velocity modifiers in the modifier stack. Radial Type Velocity Field: The Radial Field sets all the velocity vectors to point away from the local coordinate system of the velocity modifier. lf the magnitude is negative, the vector points towards the coordinate origin. A typical use case for this vector field are expanding nebulae such as supernovae and planetary nebulas. Disk Rotation Type Velocity Field: The Disk Rotation Field sets all the velocity vectors in the direction perpendicular to the cylindrical radial and the z-direction from the local coordinate origin of the velocity modifier. This velocity field is suitable for rotating disks such as spiral galaxies or accretion disks. Collimated Type Velocity Field: The Collimated Field is an easy way to set up a jet-like outflow with an opening angle as a parameter, which by default is zero. Custom Type Velocity Field: The Custom Field is fundamentally different to the others in that each of the graph tabs on the right actually represents the corresponding vector component instead of just a factor to the magnitude. Hence, the total magnitude and direction of the vector is given by the vector addition of these components. An important tool help with the velocity field modeling is the Field modifier , which allows one to visualize the vectors in the 3-D views of the 3-D Module. Modifiers: Velocity

The Size Modifier scales the mesh. Different scaling factors can be applied along the x, y and z axes. The Size operator only changes the vertex position and does not affect the local coordinate system, i.e. the reference point for other modifiers, such as the velocity field, are not changed. Name: Provide a name for the modifier that closely describes its function. Lock: When enabled, this flag keeps all the scaling factors the same. The last change in any axis is adopted for all axes. x,y,z: The scaling factor by axis. Anchor: The anchor is the xyz position in space around which the scaling will be applied. This may shift the whole object towards or away from this position, depending on whether the value is smaller or larger than one. A change in anchor position does not affect the local coordinate system, it only moves the vertices of the mesh. Modifiers: Size