Maya – Setting the V-Ray Sun direction according to location, date and time

Software:
Maya 2018 | V-Ray 3.6

To set the VRaySun photometric light source diretion according to the location in the world, the date and the time:

  1. Select the VRaySun parent node – ‘VRayGeoSun1Transform‘ and rotate it so its Z axis points to the architectural plan’s south.
  2. Select the VRaySun node – ‘VRayGeoSun1‘ and in its attributes un-check Manual Position.
    This will make the location / date / time parameters accessible.
  3. Set the GMT zone of you architectural project’s location in the world, the Date and time.
    * haven’t found how to set daylight saving time….

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Related:
V-Ray for Maya Physical Camera
V-Ray for Maya White Balance
Daylight system addon for Blender

Sample based white balance using the physical camera in 3ds max / Maya

Software:
3ds max 2017 | Maya 2018 | V-Ray 3.6

3ds max

Render a test with White Balance set to Custom with pure white color.
Let the rendering go on at least until the pixel values stabilize (the Denoiser works at lieast once..).

WB_A
Test done using custom white balance with pure white

set the white balance custom color to a color sampled from the VFB at a point that you know should be appearing completely neutral (neither warm or cold)

WB_B
White balance is set using sample from the test rendering

Render again.

WB_C
A new render done with the sampled white balance color

* Each time you want to test different sample locations you need to sample the pixels from the test rendered with custom pure white.

Maya

The procedure in Maya is identicle,
Add V-Ray Physical Camera attributes to the camera and enable them,
Create a test render with pure white White-Balance Color,
Sample the white/grey surface color in the V-Ray VFB (Render Window) to the White-Balance color, and render again.

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V-Ray for Maya Physical Camera

To access V-Ray Physical Camera functionality in Maya,
V-Ray Physical Camera attributes must be added to the camera and enabled.

1) select the camera

2) In the attribute editor open the Attribute menu and choose V-Ray > Physical Camera

3) make sure treat as physical camera is enabled

* you can add more V-Ray Attributes to the camera like this

V-Ray_Physical-camera