This page describes the V-Ray Light Meter and its use.
The VRayLightMeter node evaluates 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 or saved to a CSV file.
UI Path: ||V-Ray Shelf|| > Create VRayLightMeter button
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 z direction.
The settings in this group control the way the illumination information is represented in the view port.
Viewport Orientation – enables or disables the preview of the direction from which the light is coming.
Viewport Text – enables or disables the preview of the actual values of the illumination for each point.
Viewport 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.
– 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.
The following example shows how VrayLightMeter measures the illuminance from two lights.
VRayLightRect – default settings with Intensity multiplier of 90
VRayLightSphere: default settings
Witdth = 24
Lenght = 24
Witdth = 8
Lenght = 8
Viewport Orientation: ON
Viewport Text: ON
Viewport Colors: ON
Min = 0
Max = 1000
Measured Value: Total Illuminance
MEL Script Methods
The following methods of the VRayLightMeter node are accessible from the Script Editor.
|Calculates the values along the light meter grid.|
|vrayLightMeterSaveToCSV("VrayLightMeterShapeX", "path/filename.csv");||Saves the values from the grid into the specified text file, in CSV (comma separated values) format.|
|vray getLightmeterMaxValue <NODE NAME - STRING> [direct|gi|total]||Returns the maximum value of a lightmeter (for Direct/GI/Total light).|
- The VRayLightMeter node is based on the texture baking and render elements functionality of the V-Ray renderer.
- The VRayLightMeter node uses brute force GI with user selected GI Subdivs and 100 Bounces to calculate the measured values.