BASICS OF THE V-RAY RENDER SETTINGS author:
Wouter Wynen
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©2006 VisMasters. All rights reserved. VisMasters and the VisMasters logo are trademarks of ArchVision, Inc. All other trademarks belong to their respective owners.
BASICS OF THE V-RAY RENDER SETTINGS by: Wouter Wynen
January 2006
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Basics of the V-Ray Render Settings
INTRODUCTION This tutorial will explain very briefly many of the V-Ray render settings. A very basic 3D Studio Max knowledge is needed to be able to follow the tutorial. For more info on each topic, please refer to the online manual. It’s also a good thing if you have a basic understanding of rendering in general. Terms like Global Illumination, raytracing, antialiasing, displacement and so on should sound familiar before you start working with V-Ray. The V-Ray version I used for this tutorial is 1.47.03.
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1. Set V-Ray as the production renderer Open the render settings dialog. Then, go to the current renderer rollout and click the assign button for production renderer. Choose V-Ray from the list.
2. Extra rollouts! After V-Ray has been set as the main renderer, you’ll notice a lot of new rollouts. Every rollout with “V-Ray” in front of its name is filled with V-Ray render settings... The next steps will each cover one rollout in general.
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Basics of the V-Ray Render Settings
3. V-Ray frame buffer When enabled, the V-Ray frame buffer replaces the Max virtual frame buffer. The V-Ray frame buffer has many more options to post process images and lots of other interesting settings. In this rollout you can control the size of it by disabling the ‘get resolution from max’ check box. Rendering to V-Ray raw image file enables you to render very high resolution images, without eating up all the available RAM. The use of the V-Ray frame buffer is for advanced V-Ray users only. Don’t bother using it when you’re new to V-Ray.
4. V-Ray global switches Here you can control and You can also turn off all override many of V-ray’s maps, all filtering of maps settings, mainly used to speedetc... Glossy effects are for up test rendering. example blurry reflections or refractions. Turning them off greatly improves render time, You can turn off all displacement, lights, default very neat while doing test max lights, hidden lights and renders. shadows by just unchecking the appropriate check box! Override material can be used to give every object in the scene the same material. The “don’t render final image” button is used to let V-Ray only compute the GI Secondary ray bias: please (irradiance map for example) refer to the manual. without actually rendering the image. Forget this for now :-) Turn all reflections and refractions in the scene on or off by unchecking the check box. Very useful for testing purposes. The max depth controls the depth of the reflection/refraction (the number of times a ray can reflect/refract before it is being ignored in the raytracing process). Basics of the V-Ray Render Settings
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5. Image sampler (Antialiasing) In V-Ray, you can choose between 3 types of image samplers to compute the anti aliasing of the image. This controls how sharp and smooth your image will be, and has a huge effect on render times! Fixed rate is very predictable, but slow in many cases. Use this one if there are a lot of glossy materials, area shadows, motion blur etc... Higher subdivs means better Some testing will be needed to underquality, higher render times. stand the differences between the 3 samplers. The online documents have very good explanations on this topic, with lots Adaptive QMC is my favorite. As it’s name already indicates, it is an adaptiveof examples showing all differences. sampler, it will adapt its calculation to the situation. It will compare the quality of The anti aliasing filter can be changed if the computed pixel by some thresholds, you have problems with fine textures or and decide if it’s good enough or if therefine details in the scene. Every sampler are more calculation needed. has its own characteristics, but it is not This samplers quality is controlled by the goal of this tutorial to explain them the QMC rollout (further down in the all. In many cases you can get away with rollouts). Use adaptive QMC if you havesimply turning the filter off! many glossies, area shadows, motion blur A few filters I use often: etc. in your scene, and if you want maxi-- none mum control over the speed vs quality - Mitchell-Netravali: smooth result, good of the image. It takes some time to get controls a grip on it, but once you get it, you have- Catmull-Rom: very sharp (a bit like the full control over V-Ray with just a few result of ‘unsharp mask’ in Photoshop) clicks. - soften with radius around 2.5 (smooth and fast) Adaptive subdivision is also an adaptive method. Although very fast is many cases, it can get very slow with lots of glossy effects in the scene. It also uses more RAM memory while rendering. Use this sampler if you have large smooth areas in your scene (for example an interior with large white walls). The min/max rates control the quality, 0/2 are good values, -2/-1 are good for very fast test renders .
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Basics of the V-Ray Render Settings
6. Indirect illumination (GI) This rollout controls the main options for the GI (bounced light). Like most GI renderers, V-Ray makes a difference between first and secondary bounces. A simple spotlight will cast direct light. This light hits an object and will be absorbed a bit, but the rest bounces back into the scene. This is the first bounce. This first bounce will probably hit another object and will bounce again (second bounce) and so on until no energy is left. The direct light and first bounce will have the largest impact on the lighting look, because this bounced light has still a lot of energy. So these need to be computed very accurately to create realistic lighting. The secondary bounces are usually less important (a lot of the light energy is already absorbed, there’s less impact on the visual result), so approximations can be rougher here (interior scenes are an exception, the secondary bounces become important too).
or off with the two appropriate check boxes. An example of very visible reflective caustics is the light pattern you will see if you put a spotlight on a chrome ring lying on a table. Refractive caustics are generated for example by a glass sphere, which bundles all light that passes through it, creating a very bright spot underneath it. Note that when you want GI light to pass trough transparent objects, you must set ‘refractive GI’ caustics ON!
You can choose between different ways of computing first and second bounces, and adjust the strength of them (multipliers). Post processing options can desaturate the GI light, or its contrast. Remember that caustics is only a name for refracted/reflected light. Because light coming from a max spotlight, for example, is direct light and not GI light, you also have the ability in V-ray to render these direct light caustics.
Caustics are light patterns formed by refracted/reflected light. GI caustics are caustics created by refracted/ reflected GI light (light bounces). The standard first and secondary bounces don’t take the reflective/refractive material properties into account, only the diffuse properties. You need to turn them on
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7. Irradiance map / Quasi-Monte Carlo / photon mapping / light cache Depending on the method for first and secondary bounces you have chosen, the above rollouts will appear. They are all ways of calculating GI bounces. Each have their specific advantages and uses. I will explain these in a separate tutorial as this is too complicated for this basic settings overview. For now, remember that all these methods are ways to approximate GI lighting. GI calculations are very time consuming, that’s why methods are invented to speed things up by using approximate values.
8. Caustics Remember the direct light caustics from step 6? Well, here you can turn them on or off, and control some parameters. To get nice direct light caustics, you will also need to make adjustments in the V-Ray light settings. If I find the time, I will make a direct caustics tutorial too! A simple trick to eliminate the need for direct light caustics, is simply not to use direct lights. With only GI light, you tick ‘refractive/reflective GI caustics’ in the Indirect Illumination rollout and all caustics will be calculated according to your GI settings! Of course it is not always possible to use only GI light...
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Basics of the V-Ray Render Settings
9. Environment V-Ray allows you to override the Max environment with these controls. Use the skylight to light the scene with a ‘skylight’. If you put a map in the slot behind it, the color swatch is neglected and instead, the map is used to light the scene. You need to enable GI for the skylight to become visible. The skylight is not a direct light, it’s actually treated as first bounce, that’s why GI is needed to make the skylight visible. Note that if GI is enabled, skylight is turned off and you have put a color in the Max background, that color will be used as skylight! The other swatch controls the reflection/ refraction environment. No matter what the max environment is, your objects will always reflect/refract this V-Ray override. You can also put a map in there like with the skylight option.
*Note that these settings will not show up in the background of the render. Use the Max environment setting for this.
10. QMC Sampler The QMC sampler can be seen as a global quality control center. It controls all parameters that have anything to do with Quasi Monte Carlo calculations like adaptive QMC AA, QMC GI, Irradiance map, Glossy effects, area shadows, Motion Blur and Depth of field. The most important parameter is the noise threshold, this controls the accuracy of al the calculations. The highest quality setting is 0.001, but this of course requires the longest render time. The global subdivs multiplier can be used to lower/increase all subdivision parameters in the scene (Irradiance map, QMC GI, glossies, area shadows, Motion Blur, Depth of field,...). This is very useful for fast test renders.
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11. Color mapping Color mapping can be used to post process an image within V-Ray. Please refer to the manual for more information about the different types.
12. Camera You can choose different camera types instead of the default standard Max camera, for example fish eye lens, spherical camera, cylindrical etc... Please refer to the manual for more information about these different camera types. Depth of field is an effect caused by the diameter of the diaphragm opening of the camera. Objects that are out of focus will become blurred. The further away from focus and the bigger the diaphragm, the more the object will be blurred. Motion blur is the blur that you get when objects move very fast, or when the camera is moving. Both of these effects are raytraced, not faked with some fancy tricks, so they have a big impact on render times...
13. Default displacement These parameters control the default V-Ray displacement settings. More on displacement can be found in the online manual, with lots of illustrations.
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Basics of the V-Ray Render Settings
14. System Another rollout that controls all kinds of general parameters. Raycaster parameters are used to control the amount of memory V-Ray uses for a specific scene. In 99% of all cases you don’t need to touch these! Render region division X and Y control the width and height of a render bucket. For small render resolutions, you can lower these, for high resolutions you can increase these. Good values are squares between 32 and 128px. Region sequence alters the order in which the buckets get rendered. Distributed rendering is the process of rendering one image with different PC’s. “Previous render” controls how the previous render in the frame buffer is overwritten by the new buckets. Default geometry static/dynamic: refer to the manual.
Frame stamp is useful to print render times and such on the rendered image. Objects and lights settings control V-Ray specific properties for scene objects and lights. You can turn on/off all kinds of things locally for each object in the scene. Presets can save all or some render settings for easy and quick switching between for example test settings or high quality settings. The V-Ray log is the small window that appears while rendering, giving you some textual feedback about the rendering process. The level controls how much feedback is printed inside the box.
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Basics of the V-Ray Render Settings
About the author
Wouter Wynen has studied product development for 5 years at the university in Antwerp, Belgium. During these years, his interest in 3D modeling and visualization grew more and more. In the end, it even overpowered the interest in product design. After graduation, he founded the company Aversis, offering 3D viz & webdesign services.
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©2006 VisMasters. All rights reserved. VisMasters and the VisMasters logo are trademarks of ArchVision, Inc. All other trademarks belong to their respective owners.
Basics of the V-Ray Render Settings
