Migration to V-Ray 1.5
Adaptive DMC image sampler
Render elements and G-Buffer
Render to texture
While there are many new features in V-Ray 1.5, we have tried to keep the compatibility with older V-Ray versions where this is possible. Nevertheless, a few changes to the basic operation of the V-Ray rendering engine were made. The most important of these are outlined below. Note that there may be other changes not mentioned here.
V-Ray no longer uses randomized quasi-Monte Carlo (rQMC) sampling; instead, a modified version of Schlick sampling is used for all blurry values. For more information, see the DMC sampler section.
In previous V-Ray versions, increasing the Max subdivs parameter could lead to increased noise in the renderings when using direct GI evaluation, blurry reflections, area lights etc. This was extremely obvious when using the universal settings scenario. To compensate for this effect, a lower Noise threshold for the DMC sampler was required.
This is now corrected and increasing the Max subdivs for the Adaptive DMC image sampler keeps the same noise level without modifications to the Noise threshold. This should be kept in mind when working with older scenes where the Noise threshold was reduced - they might render slower, although the noise level will be much less. To reduce the render times again, you should increase the Noise threshold or override it by unchecking the Use rQMC sampler thresh. option in the Adaptive rQMC image sampler rollout.
There is a new option in the Color mapping rollout - Subpixel mapping. The default value for this option is off, since this produces more accurate renderings. However, the behaviour of older V-Ray versions was as though this option is always on. When combined with Clamp output set to on, this could cut off some of the noise in the image (e.g. isolated bright dots caused by reflective or refractive GI caustics). This resulted in incorrect (or biased) renderings, especially when using the universal settings scenario, but perhaps visually more pleasing because of the reduced noise.
In V-Ray 1.5, the default value for both the Subpixel mapping and Clamp output options is off. While this produces more correct renderings, you may get isolated bright dots caused by reflective or refractive caustics that did not appear with previous versions. To avoid these, you should turn both options on.
Because the Clamp output option is now off by default, very bright objects (e.g. area lights or their reflections) may appear jagged despite good antialiasing settings. To obtain smooth antialiasing for such objects like in older V-Ray versions, turn the Clamp output optoin on.
Keep in mind that if you want to use the universal settings scenario correctly, both these options must be at their default values - turned off.
Since V-Ray now supports the 3ds Max render elements interface, the old G-Buffer channels list has been removed from the renderer settings. Further on, V-Ray automatically detects which G-Buffer channels are required by the render effects and by the selected image output format (e.g. .rpf or .rla).
You have to use the specific V-Ray baking elements instead of the standard 3ds Max ones (e.g. VRayCompleteMap instead of CompleteMap etc).
The Normalize intensity option for the V-Ray light has been replaced by the light Units selector. Its action is most closely emulated by the Luminous power units setting.
The Invisible option for the V-Ray light now only affects the appearance of the light when it is directly seen by the camera or through refractions. The visibility of the light with respect to reflections is controlled by its Affect specular and Affect reflections options.