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This page provides information on the V-Ray Light Analysis Render Element.



The Light Analysis Render Element provides visual representation of the lighting intensity in the rendered frame. It collects Illuminance and Luminance information during rendering and maps it as color gradent or a grid of measured values onto the frame.

Illuminance measures the amount of light on a surface per unit area in lux. It shows how bright your surface is. Luminous intensity measures the brightness of a light source in candela.

The collected lighting information is stored in internally generated Illuminance and Luminance render channels using the respective light measurement units. Then, the Lighting Analysis Render Element simply takes the information from the selected channel and applies display modifications to it. This makes it readable with a naked eye when overlayed onto the fianal render as a post-effect.

During the render, the lighting analysis may display some approximation to the false-color image, but it should not be interpreted as being the final result. Once rendered, the VRayLightingAnalysis parameters can be adjusted further and its representation can be updated without the need to re-render.

UI Path: ||Display Render Settings button|| > Render Elements tab > LightingAnalysis




To use render elements, select from the Available render elements column and click the Add button to add the passes you wish to generate at render time. When you render the scene, the added render elements listed in the column on the right, will also render, which can be viewed from the VFB window's channel drop-down menu.

For more information on the parameters on this dialog, see the Render Elements tab page.



Enabled – When enabled, the render element appears in the V-Ray Virtual Frame Buffer. 

Filename suffix – The text added to the end of the rendered file, when saved as a separate file (e.g. myrender.specular.vrimg) 

Quantity – Choose which lighting information to be analysed. 

Illuminance (lx) – Uses the Illuminance of the rendered frame in lux. 
Luminance (cd) 
– Uses the Luminance of the rendered frame in candelas.

Min. value – Specifies which values are mapped to blue.  

Max. value – Specifies which values are mapped to red. 

Scale – Specifies how values are mapped to colors onto the frame. 

Linear – The colors are mapped in linear scale.  

Logarithmic – The colors are mapped in logarithmic scale.  

Display – Specifies the analysed data display mode. 

False colors –  Fills the frame with a gradient ranging from blue (low values) to red (high values). For the out of range values uses respectively black and white.
Grid overlay 
– Displays the values at distinct grid points over the frame. They use the same grading colors.

Grid horizontal/vertical spacing – Specifies the horizontal/vertical space in pixels between two numeric points on the grid. 

Fade background image – This option is active only if Display is in Grid overlay mode. When enabled, it fades the rendered image, so that the grid values would be more visible.  

Draw legend – When enabled, shows a legend of the false colors at the bottom of the render.  

Update button – Updates the mapped information over the frame if the parameters are changed. V-Ray Frame Buffer must be used for the updates to have effect.






Light Analysis Render showing Illuminance with False Colors display

Light Analysis Render showing Luminance with False Colors display 

Light Analysis Render showing Illuminance with Grid Overlay display