Frequently Asked Questions

 

 

Question: I have a dual CPU system, but the rendering seems not to be multithreaded. What is wrong?

Answer: Check Multithreading option in MAX's preferences - Customize > Preferences > Rendering > Multi-threading. Make sure this is On.


Question: When I render a particular object with the V-Ray renderer Dark rectangles appear at odd places on the object. When I render the same object with the Max default scanline renderer, the dark rectangles disappear.

Answer: This could happen if your object is a thin box with overlapping faces. Increase the Height or remove the overlapping faces and the squares should go away.


Question: How can I render wireframe with V-Ray?

Answer: You can use the VRayEdges texture to get a similar (although not exactly the same) result.


Question: Why the rendering of one and the same scene using different size region divisions results in significantly different rendertimes? However there is no difference in the quality.

Answer: There should be no difference in the final image, no matter what is the size of your render regions. However, every region requires some setup time. Also, when you use antialiasing filters, there is a border around each region that needs to be additionally rendered so that the edges of regions blend smoothly. As the region size increases, this additional work takes less time compared to the total render. Smaller regions allow for faster screen update - you can see your image in progress; regions save memory; regions allow easy multithreading and (more important) easy distributed rendering. The choice of slowdown/update rate is best left to the user. Values of 16-64 are recommended.


Question: Why the HDRI map has no effect on the specular level of the rendered objects?

Answer: With the standard MAX materials, the specular level is just a way to simulate shiny look for objects. For a real world object to be shiny it has to be reflective. The same applies for objects rendered in V-Ray. To achieve shiny look with V-Ray lights, glowing objects and environment maps you will need to make the objects reflective.


Question: Why do I get very weak shadows produced by the HDRI map?

Answer: For sharper shadows, get a HDRI map with a high enough dynamic range.


Question: Why do I get loss of detail when I render an object with lot of detail using V-Ray GI?

Answer: Increase the max rate - for example set to 0. You may also try to reduce the color and normal thresholds. Additionally to make the GI more detailed you can (a) reduce the interpolation samples or (b) use another interpolation method - Delone triangulation will not blur the GI, it will just interpolate it; however the min/max rate still must be enough to capture all the detail.


Question: Will the distributed engine upload the complete scene to every machine including textures etc. or will each machine just receive what is needed to render its bucket?

Answer: It will ship the full scene without the textures. Which means the textures must be visible from all the local machines. You need not share the scene itself.


Question: Can you change easily the task priority for all machines that participate in distributed rendering?

Answer: Yes, this is configurable. You can control the process priority remotely for each rendering server. For more information refer to the Dsitributed rendering section.


Question: Is the "machine list" in the distributed rendering based on machine names or IPs?

Answer: It is based on machine IPs. You can give names to each machine as you wish and they don't have to be the same as your network names. The important part is a valid IP. There is an autosearch mechanism which looks for all the available servers in the local network and includes them in the list. You can configure a box manually though.


Question: How do I use HDRI map with V-Ray to illuminate the scene?

Answer: Either load it in your environment map if you want to show it in your background or in the render panel you can load it in the section for overriding the max environment for skylight.


Question: How can I set the IOR when I use a standard material with VRayMap for the refractions?

Answer: Change the IOR of the material (in the Extended parameter roll-up of the Standard material).


Question: Does the antialiasing filter affect the irradiance map? Can I calculate an irradiance map with one filter and then use it with another?

Answer: No, the irradiance map is not affected by the antialiasing filter. In fact if you only need to compute an irradiance map, you can render without antialiasing and without a filter. You can add these later on for your final rendering.


Question: Can I render the irradiance map at 400x400 and then use it to render a 800x800 image? What will be the effect?

Answer: Yes, you can do that. The final effect will be as though you have computed the irradiance map at a lower sampling rate.


Question: Why does my fog light the scene when I use V-Ray with GI?

Answer: This is so because of the way the MAX standard fog written - it is self-illuminated (unless you use volume light, but standard fog and volume fog are selfillumed), and since V-Ray takes volumetrics into account when calculating light hitting surfaces for GI, you can see illumination coming from those volumetrics.


Question: What is the difference between a pixel and a sample?

Answer: The pixel is the smallest addressable element of an image. The main task for any rendering engine is to determine the color of each pixel. In order to do that it has to take samples from the scene. Samples are small units of information about a certain point in the scene that the rendering engine uses to determine the color of each pixel. One or more samples can be taken for every pixel in the image.


Question: What is the difference between primary rays and primary bounces?

Answer: Primary rays are those coming directly from the camera. Primary bounces occur when a ray from the camera first reflects (usually diffusely) from the surface of an object.