Migration to V-Ray 2.0
Adaptive DMC image sampler
While there are new features in V-Ray 2.0, 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.
The Adaptive DMC image sampler in V-Ray 1.5 could not properly reduce noise in darker parts of the image when the Subpixel mapping and Don't affect colors options in the Color mapping section were enabled together with the Gamma setting. This was because the image that the sampler "saw" was quite different from the actual final result and the sampler did not put enough samples in these areas. Such sutiations required lowering of the DMC color threshold to produce a good result.
This is corrected in V-Ray 2.0, but it means that older scenes might render slower than with V-Ray 1.5 because more image samples will be calculated. In most cases, this can be fixed by increasing the DMC color threshold, as it no longer needs to be very low to produce a clean image.
If for any reason you need to revert to the old (and wrong) sampling method, you can create an environment variable called VRAY_OLD_SAMPLING and give it a value of 1.
Note that this change concerns image sampling only; other sampling routines (for exmple for GI etc) are not affected.
V-Ray 2.0 cannot run with the license server from previous V-Ray versions - you must use the V-Ray license server provided with V-Ray 2.0 itself. However the V-Ray 2.0 license server will work fine for V-Ray 1.5 as well.
In addition, V-Ray 2.0 requires a different license on the dongle than V-Ray 1.5. This means that in general a dongle will contain licenses for both V-Ray 2.0 and V-Ray 1.5 in order to support full backward compatibility. The two types of licenses are not additive - using one V-Ray 1.5 license will also block one V-Ray 2.0 license. The reverse is also true - using one V-Ray 2.0 license will block one V-Ray 1.5 license. It is possible that a dongle contains more licenses for V-Ray 1.5 than for V-Ray 2.0, for example, if the user has chosen not to upgrade all of their existing licenses.