Best Practices in VRay Rendering
|VRay is a powerful tool for rendering realistic scenes from a 3D model. Generally, a model is built, a point of view is chosen, the scene is rendered, and the resulting image is edited. This workflow will show the basics of rendering in VRay, including render settings, material selection, and texture mapping.|
|Uses Tool(s)||Rhinoceros for OSX , VRay , Rhinoceros|
This workflow is missing some elements. A general summary is needed, as well as a discussion of common problems and links to external resources
This workflow can be completed using just one software tool - it would be better described as a "method" of VRay
The VRay settings is where you establish the general visual environment for the render. These settings may be different depending on the type of render you are creating, such as a night scene or an indoor scene. Settings can be stored for later use.
To begin, there are default settings provided for an interior and an exterior render. In the menu bar in Rhino, click Render->Current Renderer->VRay for Rhino . There should now be a VRay menu option. Click on VRay->Options to open the Options window. Here is where most of the settings for the general visual environment can be modified.
To load saved VRay settings, in the VRay Options window, click on File->Load , and open the settings file.
The Output settings control the size and resolution of the final rendering. The larger the rendering, the longer it takes to complete.
Uncheck "Override Viewport" to change the size of the render so that it does not match the view in Rhino. There are preset options for output sizes to choose from that are proportional to screen sizes. Click on the "Get view aspect" button to reset the output size to that of the viewport. Editing the Image Aspect changes the proportion of height to width--for example, a render with a height of 240 and an image aspect of 1.333 has a width of 320 (240 * 1.3333 is 320).
For quick test renders keep the output settings at 640x480. For presentations renders, it is best not to go below 1280x960, depending on the size of your image and desired resolution .
Controlling the Environment
The Environment settings control the overall lighting and sets the background for the render.
GI (Skylight) controls the color of the sky and/or light in your scene. It’s best to keep this at light blue (default) or white. To change the color, click on the colored box and select a different color.
To use sunlight into your scene, it’s best to do this through Rhino, not through VRay. Minimize the Render Options window. In the Rhino dialogue box, use the Sunlight command. The Sun Angle Calculator window will appear.
Check "Control sun position manually" in order to adjust the date, time, and location of the scene. Note that the time must be during daylight hours in order to render sunlight. After clicking OK, the dialogue box asks for the X, Y, and Z coordinates of the sun's position--just make these positive numbers, and adjust the placement of the sun later. Use the Zoom command and zoom to the extents of the scene to see where the sun is placed.
Open the VRay Render Options window again. In the Environment settings, click on the button with the small m (this stands for material).
In the Texture Editor window that pops up, select "Sky" under Type. Uncheck "Override Sun's parameters." To change the sunlight source to the sun that was just created, click on the Default button and apply Light 01 (if rendering multiple scenes at different times of day, the scene may contain multiple lights. The names of lights can be changed). Click Apply in the Texture Editor. Once the settings are saved in the Texture Editor, they are saved in the Render Options.
Back in the Rhino workspace, zoom to the view for the render and click on the blue cube to render, or use the Render command. The resulting image should reflect the sun's placement. To modify the quality of light, select the arrow for the sun, use the Properties command, and select Light from the drop down menu. Click on the Modify button to pull up the Sun Angle Calculator. Changing the time of day in this window is more effective and easier to do than manually repositioning the sun in 3D.
Rendering is similar to photography in many respects. Generally, after modeling the scene, a point of view is set for the camera. From this point of view, the image will be captured, and the light settings and material settings affect the resulting render.
To produce a more realistic render, check the "On" box under Physical Camera in the Camera settings in the VRay Render Options window.
There are settings that are set on a physical camera that can be set for the render. Some of the important settings to pay attention to include:
- Film speed (ISO): the greater the ISO, the more sensitive to light the camera will be.
- Shutter speed: the greater the shutter speed, the shorter amount of time the shutter will be open. This will result in a darker image because the amount of time that light is allowed to affect the sensor is decreased. The parameter is actually interpreted as 1/x, so entering a value of 4 means the shutter speed will be 1/4 of a second.
- F-number: also known as aperture. The smaller the aperture, the larger the lens opening. The aperture combined with the shutter speed are adjusted to control the camera's degree of exposure to light.
To set a point of view for the camera, it is helpful to type Camera and then "Show" to toggle its visibility. Make sure all four viewports can be seen (double click the viewport name) because the camera object will appear in all the other viewports except the one that is active. From a different viewport, the control points for the camera can be dragged to change the view. To save the view, right click on the viewport name, and click Set View->Named Views->Save , or use the NamedView command. Click Restore to change the view to a saved one.
To change the angle of the view or the type of projection, edit the settings in Viewport Properties (right click on the viewport name and click Viewport Properties).
Assigning Materials in VRay
It is best to assign materials by layer in VRay. (It is possible to assign a material to specific objects, but it is inefficient and easier to make mistakes.) A render-ready model must be organized into layers by material. To assign a material to a layer, right click on the layer name in the Layers window, then click Set Properties --> Material. Assign by Plug-in (the plug-in is VRay) and then click Create. Or, click on the M icon in the VRay toolbar.
The Material Editor will pop up. Use this editor to create materials for the scene, either by importing the material or adding a new one.
There are three parts to this window:
- Material Workspace: Here, all of the available materials are listed under Scene Materials. Default_VRay_Material is the default white material that shows up in a render without any material settings changed. Right click on the material name to pull up the actions that can be taken on the material, including renaming it or applying it to a layer.
- Material Preview: After changing settings, click Update Preview to preview what the material will look like when rendered.
- Options: These are the options for the way the material will look when rendered. Some options include reflection, transparency, diffuse, refraction, and maps.
Importing a New Material
When you installed VRay, a material library made by the developers of VRay (ASGvis) was also installed. This can be found in C:\ProgramData\ASGvis\Materials (though it depends on where you decided to save the files during installation). VRay materials can also be downloaded from different resources, the best being straight from ASGvis .
To import a new VRay material, right click on Scene Materials and click on Import New Material. Select the .vismat file of the material to be imported.
Sometimes, the material you need is not available for download. To create a new VRay material from scratch, right click on Scene Materials --> Add Material --> Add VRayMtl.
Materials become richer when they have more layers to them. Click on the "+" sign next to the material name to expand the layers. These layers add properties for emissivity, reflection, diffusion, or refraction. To add a layer to a material, right click on the desired property and click on Add New Layer. A "+" sign should appear next to the property name, meaning that the layer for that property now exists. Adjust the settings for the property in the Options panel to the right.
If the material you need is similar to an existing material in the scene, right click on the material name and click on Duplicate. Then, change the settings for material.
Applying Texture Mapping
Texture Mapping is a different way of applying materials by mapping an image file of a material texture (such as wood, concrete, bamboo, etc.) to an object.
To obtain textures, download images from internet resources or create a mapping texture by manipulating a photograph in Photoshop.
The default option in Rhino for texture mapping is Surface Mapping , which stretches the texture to the extents of the surface it is applied to. Box Mapping applies the texture to all sides of the object based on a Mapping Widget that is shaped like a box. Cylindrical Mapping applies the texture to a cylinder. Planar Mapping applies the texture to a defined plane.
To get the texture of one object to match another, open the Material Editor of the layer that currently does not have a texture. Click on the Match button at the bottom of the Editor, then select the object that has matching texture.