Chapter 5 | Modifying Vehicle Properties & Appearance
Introduction
In Virtual CRASH for Public Safety all vehicle models are customizable. You have the option to modify vehicle dimensions, axle/wheel locations, suspension limits, tire sizes, color, and material types. You can also remove vehicle components and create crush damage effects. In this chapter we review how to modify vehicle properties.
Select a Vehicle from the Gallery Browser
To place a vehicle into the scene, first left-click on “gallery” in the left-side control panel. This will open the gallery browser. The gallery browser contains a list of all 3D vehicles, 2D vehicle icons, signs, textures, and other types of objects that can be placed within scene.
The gallery browser is divided into two halves. The upper half allows you to use a hierarchy to search by object type of vehicle make. The lower half shows you which vehicles or other objects fall within the selected category. For example, when the gallery opens, the “medium” category is opened by default. “Medium” indicates the level of vehicle detail is medium to high. Hover your mouse cursor in the area shown in the red box below and use your scroll wheel to scan up or down the list of vehicle makes. Left-click on the desired vehicle make.
Next, place your mouse cursor in the lower half of the gallery browser window. Use your mouse’s scroll wheel to scan up and down the window. You will see images of the available models. If you wish to see all models, without filtering by make, then left-click “medium” in the upper half.
Left-click on the database icon in the upper-right corner of the vehicle graphic, hold the mouse button, drag your cursor into the workspace and release the left button. You should see an instance of the vehicle appear in the workspace. You can create as many instances of the vehicle as needed using this method (cloning vehicles is discussed in other chapters).
The Properties Menu
To access the properties menu, place your cursor in “Select And Move” or “Select, Move And Manipulate” mode, and then left-click on your vehicle model to select it. Next, left-click on “edit” in the left side control panel to reveal the properties menu options.
You should now see the properties menu in the left-side control panel. This displays all properties of your vehicle which can be modified (see below).
Properties > Axles
Left-click on “axles” in the properties menu to reveal the axle and tire properties (see below). Left-click to select the axle you wish to modify. You can modify properties common to both axles simultaneously by using ctrl+left-click to select multiple axles at once.
Properties > Axles > Overhang
The “overhang” parameter will adjust the distance from the front axle to the front-most vertex of the vehicle as measured along the local (vehicle frame) x-axis (see below).
Properties > Axles > COG to Front Axle
The “cog to front axle” parameter is the distance between the front axle and the local x-coordinate of the center-of-gravity as shown below. The center-of-gravity position will be indicated by a small red dot or a CG icon if (misc > “show pivot” is enabled).
Properties > Axles > Track Width
The “track width” parameter will adjust lateral distance between the contact patch centers of each tire as measured along the local y-axis. Below we see in blue, the distance from driver side to passenger side front tires.
Properties > Axles > Wheelbase
The “wheelbase” is defined as the distance between the selected axle and the axle directly ahead of it. This means by left-clicking on “axle 1” in the axles menu, you will not see an available wheelbase input field. Left-click “axle 2” (or greater) to see the wheelbase input field appear. Note that adjusting this parameter moves the select axle (and those behind it) while keeping the axles ahead stationary.
Properties > Axles > Tire
The “tire” parameter can be used to modify tire sizes. Left-click to select a single axle or use ctrl+left-click to select multiple axles at once (or left-click hold and drag down). Left-click inside the input field to the right of “tire” and type in the desired tire size data. You can also left-click on the down arrow directly to the right of the tire size input field to access the dropdown menu of preset tire sizes. You are not limited to what is in the dropdown menu. You may type whatever size data you need in the input field.
Properties > Axles > Texture
The “tire” parameter can be used to modify tire sizes. Left-click to select a single axle or use ctrl+left-click to select multiple axles at once (or left-click hold and drag down). Left-clicking the “texture” button will bring up the file manager loader. Locate the wheel texture map you wish to use and press “open”. Note, you can find some useful wheel texture maps in your Virtual CRASH for Public Safety installation area (just search the word “disc”). Left-clicking “remove texture” will reload the default wheel texture maps.
Axles > Suspension
You can modify the minimum and maximum wheel travel distance using the options in the “suspension limits” menu. Each wheel is free to move independent of the others along the local z-axis; however, suspension stop limits are enforced for both jounce and rebound. “limits-upper” controls the maximum upward compression of the suspension, whereas “limits-lower” controls the maximum downward extension of the suspension.
Properties > Size
The below diagram depicts the geometrical properties specified in the properties > size menu. These are described in more detail below.
Properties > Size > Length
Length is defined as the distance from the mesh’s rearward-most vertex to the forward-most vertex, as measured along the vehicle’s local x-axis, as the vehicle sits in static equilibrium on a perfectly flat surface. Note, if your vehicle has optional equipment mounted onto the mesh (such as the bull bars shown on the cruiser above), you will need to adjust the overall length of your vehicle to account for the extra equipment, since the published overall lengths for vehicles typically do not account for such optional equipment. In cases in cases of optional equipment protruding horizontally, you have the option to use the exclude overlapping > front/back feature described below to adjust the mesh geometry.
Properties > Size > Width
Width is defined as the distance from the mesh’s right-most vertex to left-most vertex, as measured along the vehicle’s local y-axis (see above), as the vehicle sits in static equilibrium on a perfectly flat surface. Since sideview mirrors typically are not included in published overall width. In cases of sideview mirrors, or in cases of optional equipment protruding laterally, you have the option to use the exclude overlapping > left/right feature described below to adjust the mesh geometry.
Properties > Size > Height
Height is defined as the distance from the x-y plane (ground plane) to the mesh’s highest-most vertex, as measured along the vehicle’s local z-axis, as the vehicle sits in static equilibrium on a perfectly flat surface. Note, if your vehicle has optional equipment mounted onto the mesh (such as the emergency lights shown on the cruiser above), you will need to adjust the overall height of your vehicle to account for the extra equipment, since the published overall height values for vehicles typically do not account for such optional equipment. In cases in cases of optional equipment protruding vertically, you have the option to use the exclude overlapping > top feature described below to adjust the mesh geometry.
Properties > Size > Ground Clearance
Ground clearance is defined as the distance from the x-y plane (ground plane) to the mesh’s lowest-most vertex, as measured along the vehicle’s local z-axis, as the vehicle sits in static equilibrium on a perfectly flat surface. Note, if your vehicle has optional equipment mounted onto the mesh, you will need to adjust the ground clearance of your vehicle to account for the extra equipment, since the published ground clearance values for vehicles typically do not account optional equipment. In cases in cases of optional equipment protruding vertically, you have the option to use the exclude overlapping > bottom feature described below to adjust the mesh geometry. Another strategy to set ground clearance is to use the drop down menu and scroll bar to scale ground clearance up or down until you see the vehicle’s vertical features matching to a known reference.
CG Height and Lateral Offset
As depicted above, c.g. height defines the distance between the x-y plane (ground plane), and the vehicle’s center-of-gravity, as measured along the vehicle’s local z-axis, as the vehicle sits in static equilibrium on a perfectly flat surface. C.g. offset y defines the distance between the vehicle’s local x-axis and the cg, as measured along the vehicle’s local y-axis.
Properties > misc > color
You can change the color of most vehicles by using the color drop down menu in properties > misc > color. Note, you are not limited to the colors you see in the palettes. To select a custom color, simply left-click in the color drop down menu, hold, and drag your cursor to any image visible on your display device.
Properties > faces > material
You can modify the appearance of vehicle substructures can change the color of most vehicles by using the color drop down menu in properties > misc > color. Note, you are not limited to the colors you see in the palettes. To select a custom color, simply left-click in the color drop down menu, hold, and drag your cursor to any image visible on your display device.
Once in elements selection type, you will see the “faces” submenu appear in the properties menu in the left-side control panel. Open the faces menu and left-click on the “material” button to access the available shaders (see below). Each shader has different attributes which will help you fine-tune the look of your vehicle. You are free to cycle through the various shaders to see the effect on the selected polygons. Some shaders will have glow effects while viewing in Smooth or Smooth + Textured draft preview modes. Other shaders require rendering in Direct light or Skylight to see the effect. Note, the distinction between reflective and non-reflective materials can only be seen when the scene is rendered in Direct light or Skylight.
Below we see the blue truck rendered using faces > cab on the left and using faces > barrier on the right. In both cases, the shader gets its color from the misc menu color palette drop down menu.
Note, you can also customize individual polygon faces and customize their appearance using the faces > material menu interface. Selecting faces is reviewed in Chapter 2 of the User’s Guide.
Adjusting Wheel wells
When using a vehicle from the gallery browser as an exemplar, you may need to adjust the wheel wells to better match the subject vehicle’s wheel location. It is recommended to start with a new project. After the needed modifications are made to the vehicle geometry, you can then save the file containing only the vehicle in .vps format and import the file into your main project.
To begin, make a new project and place your vehicle from the gallery browser into the scene. Set the vehicle position to position-local (x,y) = (0,0) and rotation-local (yaw, pitch, roll) = (0,0,0). Set the vehicle specifications as described above. Below, we see that our adjusted wheelbase size has the rear wheels misaligned with the exemplar geometry’s wheel wells.
To fix this, we first switch to vertex selection type (see Chapter 2). Switch to right or left orthographic view.
Next select one of the selection tools. Here we pick Lasso Selection Region. This works by left-click, hold, and drag action.
With the lasso tool selected, left-click, hold, and drag your mouse around the wheel well vertices. Release the left mouse button once you’ve enclosed all the desired vertices. Note, you can add to the selection by using ctrl+left-click, hold, and drag or do a single ctrl+left-click on the desired vertex. You can subtract from the selection by doing alt+left-click, hold, and drag or use a single alt+left-click on the vertex you wish to remove. If you wish to restart the lasso, then left-click in an empty portion of your project space to deselect all vertices and start again. Right-click to terminate the lasso tool (otherwise you’ll keep using the lasso tool). Here we see the selected vertices in red.
Next, switch to “Restrict to X” mode [1].
It is recommended to enable “Proportional Editing” (see below). You will know proportional editing is enabled because you will see its icon become highlighted. Set the “radius” input value to 1 ft. Proportional editing will modify the selected elements (vertices in this case) position or orientation as you move your mouse cursor, with the directly selected vertices (the red ones shown above) translated or rotated directly as you moved your cursor, while those within a distance equal to radius will also moved, but with diminishing magnitude as the distance from the selected elements increases. This means for crush, you will see a more natural transition from displaced to non-displaced vertex. In our case, the vertices aligning the wheel wells will move backward, but other vertices near the wheel well will also move backward to some degree.
Next, use the “Restrict To X” (red arrow) control grip to adjust the wheel well vertices as needed.
Note, if you need to include more vertices in the selection, you can use your mouse’s scroll wheel to increase or decrease the proportional editing radius value. Simply scroll up or down while the left-mouse button is held down, or go to the proportional editing menu, and change the radius setting as needed to increase or decrease the number of neighboring vertices.
Once you are finished adjusting the vertices, switch back to object selection type.
Save your project.
Importing Vehicles into Projects
To import the file into your subject project, go to Project > Import.
Change the file type to vps in the lower right corner of the Windows file browser, find your file and left-click “open”.
You should then see your vehicle appear in the project.
Tags: Change cg height, change length, change width, change overhang, change trackwidth, cg to front axle, wheel location, tire location, change wheelbase, change tire size, cg location, center of gravity location, cog location, suspension properties.
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