HDRI to Lights script
This script will read an HDR image and convert it to a collection of lights and a preview sphere. Works with panorama(latitude/longitude) type images. This was adpated from the original python script for Houdini created by Steve Twist and found in the 3D World issue number 134. His script in turn is based off of the work of Paul Debevec and his 2005 Siggraph presentation of his Median Cut technique for getting lighting information from an image.
The 3DBuzz HDRI Shader Development for Mantra module starts with an introduction video to the subject of hdri images.
https://archive.org/download/3dbuzz-arc ... v-part-01/
Usage:
FileName - Press the "..." button to choose an image file
Reduce Factor - shrinks the size of the image for processing. Max is about 1024 pixels wide. Anything above that may eat all the memory and crash trueSpace
Divisions controls the number of lights created
Radius - the size of the preview sphere and lights
Intensity Multiplier - initial brightness control of the lights
Create Lights - press to create a preview sphere and spot lights group
There may be a delay between the script returning and trueSpace becoming responsive again.
The preview sphere will use the full resolution image.
The script has a number of dependencies so we'll just say that the Unofficial Updates is required to use it.
Panorama images for the 2 trueSpace cube map hdr images can be found here:
https://web.archive.org/web/20090203184 ... ection.htm
HDRILightsGroup is created by the HDRI to Lights script
Radius - change the size of the preview sphere and lights
Cone Angle - decrease the spotlight cone angle for higher quality shadows and increase for more light coverage
Intensity - control the brightness of the spot lights
Gamma - control the contrast of the image
Show Image Sphere
Hide Image Sphere - trueSpace primitive creation has a bug where they don't work properly if the view is engulfed by a mesh, this hides the mesh so it does not interfere
Shadow - enable shadows for the spot lights
Depth Bias - smaller numbers give better shadows up to a point
Shadow Threshold - used to limit the number of lights that cast shadows. The Luminance Low and High show the range of light values. Any light below this value will not cast shadows.
Set Shadows - applies the shadow options to the spot lights
One thing I discovered while working on this is that trueSpace will store colors outside of the 0 to 255 integer range. The color picker has the limit but the colors can be stored with HDR values and maybe can even have negative number values.
The script has a number of dependencies so we'll just say that the Unofficial updates are required to use it.
