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The Taper Modifier is designed to smooth the edges of the density in a mesh as exemplified by the renderings below. It is a scaling as a function of inwards distance from the inner and outer surface of the mesh. The first image on the left shows a bipolar structure with a constant density. Here the emission goes right up the mesh and make evident the coarse mesh structure. In the second image a Taper Modifier was applied with the Taper function as shown below the render. As configured it generates a gentle glow around the surface. The render on the right has a different Taper function. It shows how it can be used to generate more complete multi-shell structures. Note that each hump in the Taper function generates two shells, one from the outside surface and a second from the inside surface. If the mesh has no inner surface, only one shell is generated. Note that for complex high resolution meshes the Taper Modifier is computationally expensive. So, balance between the computing time and the need for it. Much testing can be sped up by temporarily disabling the Taper Modifier while it is not needed. Name: Provide a name for the modifier that closely describes its function. Taper: Opens a graph to set the Taper function. The Taper function is most conveniently set up as a Point function. To smooth the edges, set the value to zero at position zero and transition to a value of 1 at the desired distance from the surface. Note that this transition scale does not change with position in an object. It may therefore not get to 1, if there is a shell that is thinner than the transition scale. This is the case in the example below, where the shell becomes thin towards the center and therefore the emission very low. This can be compensated for partially by adjusting the Magnitude graph. Magnitude: A graph that allows one to compensate for "lost" emission, from the taper in regions of these shells. Modifiers: Taper

Physics Module Overview In the Physics Module you define the radiative properties of gas and dust components. Materials or "species" are set up which then are assigned to the objects from the 3D Module . This section covers how to access and use the interface functionality. For a more detailed account of the underlying physical and numerical procedures and assumptions, please refer to the Theory section of the manual or to the PDF document "Radiative Transfer in Shape" . In general, we have tried to keep the physical calculations in line with the general philosophy of Shape, i.e. keep it simple and fast, but good enough to capture the most important phenomenology to allow qualitative and first order quantitative analysis. Units: Note that contrary to most of the astrophysics literature, in Shape we use Standard International (SI) units, i.e. MKS units based on meter, kilogram and seconds. For example, astronomers used to thinking in terms of particles per ccm should multiply all the densities by 1e6 before they put them into the density modifier. If needed, unit conversions can be done easily on a number of websites, e.g. at UnitConversion. Workflow The basic procedure is to define material species in the Physics Module where you specify the radiative properties. The species are then assigned to a selected object in the 3-D Module using the Species drop-down list in the General tab. By default, i.e if you do not specify a species, an objects has purely emitting species that is proportional to the density squared (n^2) To change that default species you first select a basic species from the Species list that opens by clicking on the blue "+"-button on the toolbar at the top. Select the species in the species list and edit its properties. Selected species can be removed from the list by clicking on the Remove button on the main menu. Copy ing is a good why to use an existing species as a basis for a new one by just modifying some of its properties. The Sort button sorts the species in alphabetical order. Selected species can be saved to disk individually or in groups using the Save button . This allows one to create a library of repeatedly used species. They can be loaded into any other project using the Open button. Custom Species: The most likely and general species that you can choose is the Custom species. It allows to define all its properties manually. We discuss this species in some detail. On the right there is a screenshot with the general options . Name your species in a descriptive way that makes it easy to identify. This becomes important in complex projects with many different species. Enable tick box: Species can be disable by switching off the Enable tick box . If more than one object use this species, they will all be switched off. n scale: The n scale parameter allows you to multiply the density n of all objects that use this species by this factor. The resulting density will be used only for this species. Other species that an object may also use will not be affected by this factor. This allows to use different scales for the density depending on the species but specifying a single object mesh and density distribution. Emitter boost: If the scattering and/or ionization options are used, then for this species only, the local brightness of the received emission from the emitter is multiplied by this factor. This is useful, for instance, when you need to brighten the objects scattered light without changing the emitter itself or the intervening absorption. Color: In the color rendering mode by default an object is rendered with the color assigned to the mesh in the 3D Module. However, the rendered color can be changed easily without changing the mesh color by clicking on the color swatch (white rectangle) and selecting a different color. For this to take effect switch on the Override Color tick box. When selected, the color swatch above the flag determines the color of the object and overrides the color resulting from the physics setup. NOTE: There are many other ways to change the rendered color of an object using the spectral settings for the emission. They are explained below in their respective parameter settings. Contribution : In the Contribution section different contributions to the radiation transfer can be enabled or disabled. They include the Emission (on by default), Absorption, Scattering, Ionization. We can also specify whether for ionization. If you do not wish to define the Absorption explicitly, then it can be calculated using Local Thermal Equilibrium (LTE) conditions. For that switch on the Absorption, LTE and Calculate K(j) flags. You define the emissivity, absorption and scattering coefficients as a function of wavelength. First activate one of these coefficients in the Contribution area (there may be more than one active). Then Edit their wavelength dependence by setting up the panel that pops up in a separate window after clicking on the corresponding Edit button. Coefficient: The pop-up panel for each coefficient mainly consists of an analytic function f(x) that is set up in the Function tab at the bottom, A display and control panel of such functions in the middle and the graph of the functions at the top. In the graph, when using an analytical function, the reserved variables n and t give direct access to the density (by number) and temperature fields, respectively, as provided by the corresponding modifiers in the 3D Module. The x variable in this graph refers to the wavelength in meters. Remember that the meaning of x varies by context throughout Shape. Spectral distributions from external data can be used, too. To do this remove the default function first by selecting it in the center section of the panel and clicking on the Remove button. Now click on Add and from the pop-up menu select Point-Function. Now you can load the external data file by clicking on the Load button. The data format is ASCII in vertical column with the wavelength in meters in the first column and intensity in the second column. For the Scattering and (Photo-) Ionization coefficients the same setup is required as a function of wavelength as for the emission coefficient. For scattering, in addition, a scattering function as a function of angle may be defined via the Phase Function . In this context the variable x is the angle in units of radian. By default there is a Henyey-Greenstein with the coefficient g=0 (isotropic scattering) applied. The coefficient g can be set in the Variables tab (or in the Math Module vía a Global Variable). Note that for scattering to work, you need at least one emitter objects in the 3D Module. Dust Species: The dust species has the options to contribute by Emission , Absorption and Scattering . The grain attributes include the range of radii (assuming a power-law distribution with parameters a, a_min, a_max, q), the index of refraction with the real part n and the complex part k. k controls the absorption. Both, n and k can be set as a function of wavelength, by editing the corresponding graph (click on the Edit button). The default option Custom in the Type drop-down menu has a simple default setup, which can be changed as required. There are a few additional options from the Type drop-down list approximating different types of grains. Here the index of refraction n and the absorption coefficients are based on data. A graph of these can be seen by clicking on the corresponding Edit button . To fully appreciate you might have to adjust the settings of the graph (right-click) The Scattering currently is single scattering. Dust scattering calculations have the option to include a scattering phase function. To see and edit the function click on the Edit button to the right of the label Phase Function . The preset is the Henyey-Greenstein function . The single parameter g of this function can be changed in the variables tab of the graph. The user can change this function. Note that in this context the variable x stands for the angle in units of radians . For scattering calculations remember that you need at least one Emitter object in the 3D Module. The properties of the Emitter can be set after you select Emitters from the Object Type drop-down menu at the top-right of the 3D Module. The default dust model is an approximation to the Mie model. For a the full Mie computer enable the corresponding flag. For more details on the approximate Mie calculation see the document "Physics in Shape" . Atomic Species: The atomic species allows to calculate the emission properties based on the atomic transition coefficients and the physical conditions like density and temperature in the object. NOTE: Usage of atomic species for the calculation of emission and absorption requires detailed knowledge of the underlying physics. We recommend the application of this option only for users that are experienced in this area. Testing of the atomic calculations in Shape has been limited so far. It is advised you solve your own test problems comparing the results either with analytical calculations. You have the choice from two databases for the atomic coefficients: Kurucz and Chianti . To apply one or the other database select the Database at the bottom of the Species Panel. Now select the Ionization State of the species in the Misc panel of the Options. For hydrogen the ionization state has to be set to "0", because lines only occur for neutral hydrogen, even thought they might come from a recombination. Processes that involve free electrons, i.e. Bound-Free (BF), take the next higher ionization state into account automatically. Now select the Database for this particular species from the drop-down menu. Click on the Reload button to read the lines. If the background of the Element label changes from red to green, then you successfully read the lines. If it is still red, one or more of the settings are incorrect. To see a listing of the lines and their atomic properties click on the View Lines button. It opens a table of the atomic properties in the database. If you want to see only the lines in a certain wavelength interval, you can set Constraints for a minimum and maximum wavelength, as well as for the minimum and maximum Einstein coefficients (e.g. to select for allowed or forbidden lines). The Contributions area allows you to select from various radiative process to be included in the calculations. The label B stands for Bound and F for Free. Note that not all processes are available for all the atoms, except for hydrogen. The numerical factor the right of the contributions is a scaling factor. By default it is set to 1. The toolbar of the Physics Module

Modifiers The Image Texture Modifier uses an grey-scale image to control density or other physical properties as a function of the image pixel intensity. It is similar to the Image Displacement Modifier (IDM) . Refer to the page of the IDM for details. Here we will describe only the differences to the IDM. This allows one to use actual images to influence them model density distribution. As shown in the example on the right, a potential application is in the modelling of spiral galaxies, where we also made use of the IDM with the same base image. The Image Texture Modifier (ITM) was used to better define the density and brightness structure in addition to the overall shape produced by the IDM. The ITM "projects" the density distribution given by the image along the direction of and starting at the position of the Gizmo through the mesh. If not modulated by other modifiers, the ITM produces a constant density along the direction of projection. For a more realistic distribution it should be further processed in that direction using, e.g. the Taper Modifier. 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. Variable: Select the physical variable on which the ITM shall operate. Operation: Select the operation the ITM shall perform on the physical variable. Radial: Select this option if you wish the displacement to be radial from the origin of the Local Coordinate System of the mesh. Filename: Click on the button on the right to open the file selection dialog to open the image file to be used to the ITM. 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. 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. 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. Modifiers: Image Texture

Translations and rotations are non-deforming transformation that change the position and orientation of an object, respectively. In Shape there are three groups of these transformations that distinguish themselves through their effect on the local coordinate system or the restrictions on their directions with respect to the observer. The Translation , Rotations and PA/Inc Rotation Modifiers have the important property that they carry along the local coordinate system and operate in the coordinate system that is obtained after previous translations and rotations. Contrary to these, the Displacement and GeoRotation modifiers only transform the geometry. i.e. the mesh position and orientation as an enclosure for the region to be rendered. All coordinate information for the local properties, such as density, velocity, etc., does not change. These are according to any prior transformation of the other type. Commutative Properties: Since several of the Position Transform can be concatenated in the Modifier Stack, it is important to know whether the order in which they are applied changes the result or not. Translations among themselves can be interchanged without changing the outcome (they are commutative). However, combinations of rotation with translations or other rotations are not commutative and therefore the order in the Modifier Stack is very important. So, make sure they are in an order that produces the desired result. Translation: Moves the object to a new position in the World Coordinate System. The local coordinate system is carried along. When using the interactive System Translation from the System tab on the right side of the 3-D Module, a new Translation Modifier is added to the Modifier Stack if there is not one already at the end. This modifier can then also me changed numerically. By pressing the x,y or z keys while interactively moving an object, the translation can be restricted along these axes. Rotation: Rotates the object in the current coordinate system. The local coordinate system is carried along. If there is a Translation applied before, then the Rotation is still applied around the translated coordinate system. When using the interactive System Rotation from the System tab on the right side of the 3-D Module, a new Rotation Modifier is added to the Modifier Stack if there is not one already at the end. This modifier can then also me changed numerically. By pressing the x,y or z keys while interactively rotating an object, the rotation can be restricted around these axes. PA/Inc Rotation: Rotates the object in the coordinate system observer´s coordinate system as inclination Inc and position angle PA . PA rotates around the line of sight with zero along the world y-axis (up). Inc rotates around the horizontal line in the plane of the sky with zero in the plane of the sky. The inclination Inc is applied first and the the position angle PA.. Displacement & GeoRotation: These two modifiers have the same functionality as Translation & Rotation, except that they only transform the mesh, but do not alter the current coordinate system. This means that other modifiers such as density, velocity, etc., will remain centered at the same position. This is often useful when a mesh is a substructure of a larger object. In such a case it is often useful to have instanced copies of modifiers that are meant to remain the same as those of the main structure or other sub-structures. Modifiers: Position Transforms Translation, Rotation Displacement, GeoRotation PA/Inc Rotation

Modifier Module Overview When a project becomes complex and there are many similar modifiers the Modifier Module helps to manage modifiers with bulk operations that change parameters for more than one of them simultaneously . On the right, the Modifier Module contains a list of all modifiers that have been set up in the project. The list has four columns that classify the modifiers and help identify and select them. Clicking on the head of a column groups the list according to that property in alphabetical order. This allows to easily work with a certain type of modifier. Different background colors for the fields further helps with the the classification and reduces mistakes in the selection of modifiers. The first column contains the Type, which can be Density, Taper, Point, Bump, Squeeze, etc. The second column indicates the Group the modifier belongs to, such as Particle, Transform or Geometry. The third column contains the name that the user gave to the modifiers. If no name was given, then this field is empty. The fourth column contains the name of the object the modifier is applied to. Select a modifier by clicking anywhere on its row in the list. Selected modifiers are highlighted in blue. On the right side, the parameters of a selected modifier are shown. The parameters can be changed there. To select multiple modifiers keep the Ctrl key pressed while you click on the modifiers to be included in the selection. To select all modifier within a certain range in the list, select the first one and the use Shift-click to select the last one. All modifiers in between will then be included in the selection. The parameters shown on the right will be those of the first modifier selected in the set. When you change parameters with more than one modifier selected, all selected modifiers will now have this parameter value. Filter: Use the filter function to display only a subset of modifiers. To achieve that start typing a word in the Filter text field. For instance, if you would like to see only the Texture Displacement modifiers, then type "Texture Displacement". You can use any word that may appear in the four columns to filter them.

Filamentary texture generator in Shape Key Sub-System: Particles Many astronomical objects, especially nebulas have filaments with complex structures. Often these can not be reproduced easily as analytic or point functions of coordinates. Particles are a way to place emission in specific regions without the limitations of a functional description. The particles serve as small spherical regions where the overall gas distribution will be sampled for rendering. The advantages are, however, somewhat balanced by disadvantages related to the non-continuous nature of particles and the way they are placed in the model. Therefore careful evaluation should be applied to whether this is a suitable tool for your goal. On the right is an example of spiral arms applied with the Draw tool on the surface of a flat disk. Below are the renderings with (right) and without smoothing (artificial "seeing") applied. General Workflow Particles can be applied to a mesh by two methods: 1. using the "Draw" tool to place them at specific positions on a mesh using a 3-D cursor that slides over the surface mesh.2. randomly over a surface or filling the volume. The volume particle number density can be controlled by the Distribution function. Once a first set of particles has been applied and the density the distribution of particles can be adjusted using the Draw or Erase tools. The physical properties of the particles, such as density or temperature, can then be adjusted as a function of position using the usual modifiers. General Parameter Panel For the particles to render at all, in the General Parameter Panel of the object select "Particle" from the Input drop-down list . Particles tab In the Particles tab you control the uniform but random distribution of particles in the mesh volume or along its surface. Num: The number of particles to be distributed Size: The size of the marker circle in the 3-D views of the 3-D Module. Displayed: The percentage of the total number of particles that is to be displayed in the 3-D views of the 3-D Module. If the number of particles to be rendered is very large, it may be convenient to display only a fraction of them in the 3-D views. Seed: The seed of the random distribution of particles. Change this number to change the distribution. Container: From this drop-down list you can select between Volume and Surface. For Volume the particles will be evenly distributed within the volume of the mesh. When you choose Surface, they are placed on the surface. Buttons: At the bottom of the Particles tab is the button (left) that needs to be pressed to apply the particles or redistribute them according to the parameters of this panel. The second button is used to save the parameters in an ASCII file including all its attributes, including their position in Cartesian World Coordinates, their velocity, the density n and pressure p. The third button open a dialog to load external data as particles. This allows one to visualize a variety of external data, including hydrodynamic simulations in order to extract spectral information such as position-velocity diagrams. Using this dialog a variety of ASCII data formats can be loaded. Draw particles: In order to place particles in specific positions that can not be described with functions, Draw and Erase tools is provided. You access the particle tools via the buttons in the Particles tab on the left side of the 3D Module as shown on the right. When the Draw or Erase buttons are activated an orange 3D cursor in the form of a cylinder appears on the surface of the active mesh. You can move it around with the 2D cursor, it will stick to the surface and place particles on the near side of the mesh at a certain rate within the volume of the cylinder. Using Alt-left-drag places the particles on the far side . Draw tool parameters: The parameters for the Draw tool can be adjusted in the Tools tab on the right side of the 3-D Module. This tab displays the parameters of the currently active tool. The Name parameters identifies the currently active tool. Since the Draw tool is a cylinder , its geometric parameters are: Radius and Length in units of the spatial domain. The orientation of the 3D cursor is always with its axis perpendicular to the local surface mesh triangle. Transparency: using the slider the transparency of the 3D cursor can be adjusted. # Particles: The number of particles that will be placed at random positions in the volume of the 3D cursor per unit of mouse movement. The value should be 1 or above (not as shown in the image or the parameter panel on the right). If set to 1, a single click places 1 particle at a random position in the volume. To place individual particles at very specific positions, choose a small radius and length for the curser and click at the desired position. Density: The density of the particles. This can be modulated or scaled as a function of position using density modifiers in the mesh object with the Scale or Add options, including textures. Particle Size: This parameter is currently decripated. The radius of the rendered particle is now set in the Render Size parameter located in the Input parameters of the objects Input type (Particles). If you enable the Pixels flag, the Render Size is in terms of pixels in the Render Module. Modify: When activated the 3D cursor does not generate new particles but modifies the properties of the particles that come into its volume to have the current properties set for the tool, mainly the density. Erase tool: The Erase tool is activated with the corresponding button in the Particles tab to the left of the 3D views. It deletes particles inside its volume. It has only the parameters of Radius , Length and Transparency for the cylinder that makes up the tool. The Input Parameters dialog that opens when you click on the Options icon after selecting Particles as Input in the General tab of a mesh object.

Top of Page Basic Workflow Overview 3-D view ports Menu Bar Primitives Objects, Tools & Lights tabs Transform tools 3-D Module Basic Workflow Basic workflow: Interactively add the geometric elements of your object in the form of primitive polygon meshes (Primitives) that you can access at the top menu bar of the 3-D Module. These meshes will serve to encase the volumes that will constitute the different parts of the model. Then you modify the simple structure of the Primitives using what we call Modifiers, which give the objects new geometric structure and physical properties as a function of position in space. Using the Physics Module, you then assign the material and radiation properties to the meshes. Finally, the model is rendered with the Render Module and some of the observational properties can be displayed with the (Channel) Maps and Graph Modules, where the observational data can be included and compared with the model results. If the results are not satisfactory, the model will be adjusted until a satisfactory match is found between observations and model. Overview of the 3D Module : The purpose of the 3D Module is to set up your model interactively. This module is divided in several sections, the interactive 3-D view ports , the Menu Bar at the top, Objects, Tools & Lights tabs on the right and Transform Tools on the left. 3-D view ports: By default there are four view ports that can simultaneously show you the same number of different views of your mesh model. Several of these camera views are aligned with the coordinate axes (initial defaults: Front, Right). The Free-Form view can be changed arbitrarily using mouse input after selecting the Camera > Orbit tool from the Transform Tools to the left of the 3-D view ports (see Transform Tools for details). A special view port is the Render view, since it represents the view that will be used for rendering in the Render Module. This view can be controlled interactively with the Mouse in the same way as the Free-Form view, but also numerically with Image and Camera parameters in the Render Module. Right-click menu: When you right-click on the area of a 3-D viewport, a menu opens that allows you to set a number of properties of this particular view. Camera: Select a different camera view for this viewport. Save Image: Save the mesh images of the viewports. It saves the image of all viewports in one image. If you want to save only a single view, then use the Maximize command from the right-click menu to open a single view in the 3-D view space (to go back to the four viewports, right-click again and select Restore). Make sure to provide a filename with a valid image extension. Most common image formats are supported, such as .png (recommended), .jpg, .gif, etc. (example: image1.png). The Save Image function is the same as that of the Save button in the 3-D Module´s top menu bar. Saving your viewport images with this function does not include the colored coordinate axes or the viewport labels. To saves these you can make screenshots of these areas. Properties: In this dialog you can set a few parameters for the individual view port. Scene alpha: This parameter changes the transparency of the whole polygon object scene, so a comparison with observations or the rendered scene may be easier with lower alpha values. Background: This setting selects the background image of the scene between None, Observed and Rendered, which enables you to compared the corresponding images with the mesh. Including the Observed data is useful to place and shape mesh objects according to the observations. Note that a direct comparison with observed data makes only sense for the Render image. Sometimes, comparing the observed images with other views might be helpful when checking for symmetry properties. Maximize: For more detailed inspection, this command fills the space of the four viewports with a single one. Restore the four views using the Restore command in the right-click menu. 3-D view ports Overview Menu Bar Menu bar: The Menu Bar of the 3-D Module provides quick access to a number of commands (left section) and the creation of Primitive mesh objects (right section). Save: Save the mesh images of the viewports. It saves the image of all viewports in one image. If you want to save only a single view, then use the Maximize command from the right-click menu to open a single view in the 3-D view space (to go back to the four viewports, right-click again and select Restore). Make sure to provide a filename with a valid image extension. Most common image formats are supported, such as .png (recommended), .jpg, .gif, etc. (example: image1.png). Saving your viewport images with this function does not include the colored coordinate axes or the viewport labels. To saves these you can make screenshots of these areas. Import: This command allows you to import objects from a different project. A file selection dialog opens to select the project from which to import objects. Then a second dialog allows your to select one or more objects (shift-click for selecting multiple objects). Note that it is divided into tabs for different types of objects which have to be imported separately. Options: The Options dialog contains settings for viewing coordinate grids in the 3-D viewports and other options that might be helpful during modeling and for publication of model meshes. Undo: This command opens the Undo Stack utility. It shows recent commands that can be undone and redone. You can select which commands to undo or redo and set the maximum number of commands to be held in the stacks. Additional Undo options exist for example for the Path vertex objects which can be undone with Ctrl-z or redone with Ctrl-y. Primitives: The most important functionality of the menu bar in the 3-D Module is to provide quick access to the creation of various Primitives, i.e. basic geometric mesh objects that can be described with only a few parameters. Create a new primitive object by a first click on the corresponding icon, then click on one of the 3-D viewports and immediate drag the mouse to the right to increase the first parameter of the primitive. When the first size is adequate, click again and drag to the right to increase the second parameter (if necessary). One click and drag to the right for each parameter (sphere has one, cone and plane have two, “cube” has three) of the primitive object and then one more click to finish. Your object appears in the Systems folder of the Objects tab located to the right of the 3-D viewports. By default the names of the objects is PS_#, where # is the number in order of creation. This name can and should be changed to something more descriptive in the General parameters menu of the drop-down list to the right of the Objects folder tree. The detailed properties of the individual objects can be changed after selecting it by clicking on the objects name in the Objects stack, where it will be highlighted and in the 3-D viewports the corresponding mesh will turn white, if the Show status flag in the General properties is activated (this is the default). The Object Properties drop-down list contains five different parameter sections: General, Particles, Modifiers, Primitive and Fields. Click on Object Properties for a link to a more detailed description of its content. Primitives Objects, Tool and Lights tabs: The parameters of objects and different tools can be set in the Parameter Tabs on the right side of the 3-D Module. There are three tabs available for the parameters. Objects: handles the parameters of the objects in the 3-D viewports. Tools: allows access to the parameters of tools such as the Draw Tool or Erase Tool for particles accessed in the corresponding tab on the left of the 3-D Module). The parameters in the Tools tab appear once the tool has been activated. Lights: change the lighting properties of the 3-D viewports by changing the properties of the default Ambient Light or adding, deleting and changing the positions and parameters of other types of light. A more elaborate lighting scheme is often useful to create schematic illustrations using the mesh objects. Objects, Tools & Lights tabs Transform tools: On the left side of the 3-D Module there is a set of tabs with a variety of tools, most of which interactively change the positions and orientations of various types of helper objects: Cameras: change the view points of Render or Free-Form view ports interactively. Systems: change the transform properties of individual objects (Systems) of the scene. Widgets: change the local coordinate system of the selected tool or modifier. Vertices: with these tools individual or a group of vertices of meshes are manipulated for very detailed local changes of the meshes. Particles: draw and erase Particles on and around meshes that serve as supports. This allows very detailed structures to be added to an object than can not be easily generated with meshes or procedural filament tools. The parameters of the Draw and Erase particles tools are set in the Tools tab on the right of the 3-D Module. Transform tools Objects Tree: The objects tree is a hierarchical list of the current objects in the scene. They can be collected in folders and sub-folder. With the tick boxes to the left of each object an object can be switched on or off. Similarly switching on or off a folder does the same for all objects in a folder. New objects are placed in the default "Systems" folder. New folders are created using the "Add new folder" button at the bottom left. Copy objects with the copy-button. The copy is then placed at the bottom of the list in the same folder. Move objects and folders around within the object tree by dragging and dropping. Delete objects and folder with the delete button at the bottom of the panel. The color of the symbol to the left of the object name is the same as the mesh color and helps to identify the object in the 3-D views. If the object is not enabled, the color of the symbol is grey.

Introduction Why Shape? Images inspire us. Images lead to ideas. We made Shape as a tool to test inspirations. Play True or False. By finding out whether an idea works or not, either way, with Shape you can find new insight into nature for yourself and others. 3-D visualizations of astrophysical objects and phenomena in science and the media are often made with non-scientific software or the result is too abstract most of the time. Shape combines both worlds, putting as much computational astrophysics as possible to the service of research and outreach. Whether you are looking for profound scientific insight or photorealistic volumetric visualizations of what is going in the universe around us. the odds are you are in the right place. What makes Shape different? We want Shape to be easy to handle and fast to learn, so you can quickly play with the results and change things, before an inspiration evaporates. Shape is different from other astrophysical modeling tools, since it is based on modern interactive 3-D modeling technology similar to the one used for special effects, video games and architectural visualization. We combined this technology with custom made rendering, visualization and plotting techniques drawn from numerical astrophysics. Shape allows you to build astrophysical structures and processes in a controlled way from very simple structures to highly complex environments. They can either be static or variable and are build either from polygon meshes, hydrodynamic simulations or a combination of both. The combination of hydrodynamic models with polygon mesh objects in astrophysics is a unique feature of Shape. Shape continuously evolves, following the users' ideas and needs. It is interactive and the physics is highly customizable through the interface and, make sure to note: all this without the need for programming by the user .