VRayLightMeter Overview

The VRayLightMeter helper allows the user to evaluate how a scene is illuminated at a given time during the day or how it is affected by different light sources. The information can be displayed in the viewport and it can be also saved to a CSV file.

VRayLightMeter

Active - enables or disables the VRayLightMeter helper.

Dimensions

The options in this group allow us to specify the dimensions of the light meter tool and its resolution - the number of points at which the illumination will be measured.

Width - the width of the VRayLightMeter.

Length - the length of the VRayLightMeter.

Width segs - the resolution of the VRayLightMeter in the x direction.

Length segs - the resolution of the VRayLightMeter in the y direction.

Preview

The settings in this group control the way the illumination information is represented in the view port.

Orientation - enables or disables the preview of the direction from which the light is coming.

Viewport text - enables or disables the preview of the actually values of the illumination for each point.

Pseudo Colors - when enabled the VRayLightMeter will display a gradient to illustrate the variation in the illumination.

Logarithmic - changes the illumination scale to Logarithmic for the purposes of displaying it in the viewport . This is useful when there is a great variation in the illumination.
Min - specifies the minimum illumination displayed in the viewport in lux.
Max - specifies the maximum illumination displayed in the viewport in lux.

Measured values - specifies which part of the illumination in the scene will be measured:

Total illuminance - the total illuminance will be measured - this includes direct light, GI, and light coming from the environment.
Direct illuminance - calculates only the illumination from direct lighting.
Indirect illuminance - calculates only the effect of the indirect illumination.
Daylight factor - calculates the illumination coming from the sky.

Calculate - hitting this button will calculate the measured values at the grid points of the light meter helper.

Save to CSV file - this button allows you to save the result in a .csv file.

MaxScript Methods

The following methods of the VRayLightMeter object are accessible from MaxScript.

VRayLightMeter Method	Description
calculate()	Calculates the values along the light meter grid.
saveCSV<filename>	Saves the values from the grid into the specified text file, in CSV (comma separated values) format

Notes

The VRayLightMeter helper is based on the texture baking and render elements functionality of the V-Ray renderer.
The VRayLightMeter helper uses brute force GI with 100 subdivs and 100 bounces to calculate the measured values.