Environment Mapping Tools

Forked from https://github.com/cedricpinson/envtools

A set of tools to manipulate environment for Physical Based Rendering

Use for https://github.com/todaylg/three-viewer

Environment Generation

process_environment.py generates a full set of data ready to use for PBR. It calls other program to generate thumbnail/irradiance/specularggx and config file. At the end of the process you will have:

• A thumbnail
• A config file that contains the spherical harmonics
• Cubemap / Panorama files encoded in rgbm/rgbe/luv

Build environment with docker

You can get some environment from http://hdrmaps.com/freebies to test the tools

Build Container:

docker build -t todaylg/envtools ./

Start:

docker run -v $(pwd):/data -t todaylg/envtools process_environment.py /data/test.hdr /data/result/

Build only lut format:

docker run -v C:\Code\C++\envTools\data:/data -t todaylg/envtools process_environment.py --nbSamples=1024 --sample-rotation 18 --write-by-channel --encoding 'luv' --approximateDirectionalLights --gz --zip --fixedge --pretty --cubemap-only /data/test.hdr /data/result/

Light:

docker run -v $(pwd):/data -t todaylg/envtools extractLights /data/test.hdr

Sub Commands

Spherical Remapping

This code supports reprojection and resampling between any two of the following spherical image projections. A high-resolution example image of each type is included.

	The rect type corresponds to the equirectangular projection, much like the common map of the world. It represents the full sphere, though with significant distortion near the poles. (Example.)
	The ball type corresponds to a photograph of a mirrored sphere, or "light probe". It represents the full sphere, but with significant distortion toward the back. (Example.)
	The dome type gives a "dome master". This is an image suitable for projection onto a fulldome planetarium. The view looks up and the radius varies linearly with latitude. It represents only half of the sphere. (Example.)
	The hemi type is mathematically identical to the dome type, though the view faces forward instead of up. This corresponds to a photograph taken with an 8mm "fisheye" lens. This too represents only half of the sphere. (Example.)
	The cube type corresponds to an OpenGL cube map texture, and is the best choice for use in real-time 3D rendering. The TIFF contains each of the six cube faces in a separate page. The cube faithfully represents the full sphere with minimal distortion. (Example.)

The output is sampled using one of several sampling patterns, which give a quality-speed tradeoff.

	cent … One sample at the centroid of the output pixel
	rgss … Rotated-grid super sampling
	box2 … 2 × 2 super sampling
	box3 … 3 × 3 super sampling
	box4 … 4 × 4 super sampling

This tool remaps the input image src.tif to the output dst.tif. The sample depth and format of the input TIFF is preserved in the output.

envremap [-i input] [-o output] [-p pattern] [-f filter] [-n n] src.tif dst.tif

• -i input

  Input projection type. May be ball, cube, dome, hemi, or rect. The default is rect.

• -o output

  Output projection type. May be ball, cube, dome, hemi, or rect. The default is rect.

• -p pattern

  Output sampling pattern. May be cent, rgss, box2, box3, or box4. The default is rgss.

• -f filter

  Input filter type. Maybe nearest or linear. The default is linear.

• -n n

  Output size. Image will have size n × n, except rect which will have size 2n × n.

Irradiance Generation

This tool generates an irradiance environment map from a given environment map and print spherical harmonics in the console. It uses the same code in CubemapGen from amd and patched by Sebastien Lagarde.

envIrradiance [-n n] [-f toogle seamless cubemap] in.tif dst.tif

• -n n

  Output size. The output will be a 32-bit floating point TIFF with six pages, each n × n in size.

• -f toogle seamless cubemap

BRDF LUT generation

This tool generates the brdf LUT like in UE4

envBRDF [-s size] [-n samples] output.raw

• -s size

  Output size. The output will be a rgba uint16 fixed integer.

• -n samples

  Number of samples used to generate the lut.

Prefilter environment

This tool generates prefiltered environment like in UE4

envPrefilter [-s size] [-e stopSize] [-n nbsamples] [-f toogle seamless cubemap] in.tif out.tif

• -s size

  Output size

• -e stopSize

  This limit the size of texture used to interpolate the roughness in different LOD. For example if you limit the size to 8, the roughness will be spread between size and 8.

• -f toggle seamless cubemap

  Generate cubemap with the stretch code from amd cubemap for seamless cubemap.

• -n samples

  Number of samples used to generate the lut.

Background generation

This tool generates cubemap environment blurred to be used as background environment

envBackground [-s size] [-n nbsamples] [-b blur angle ] [-f toggle seamless cubemap] in.tif out.tif

• -s size

  Output size

• -b blurlevel

  The blur level is the radius angle of the cone used to make the blur

• -f toggle seamless cubemap

  Generate cubemap with the stretch code from amd cubemap for seamless cubemap.

• -n samples

  Number of samples used to generate the lut.

Lights Extractions

This tool generates lights list in JSON format, extracted from the environment

extractLights [-a max_light_areas] [-l max_light_length] [-r ratioLight] [-n numCuts] [-d] [-m num_lights] file.hdr|exr

• -m num_lights

  export JSON max number of lights and cull others. ( default is 1, 0 is unlimited)

• -a max_light_areas

  A max limit to the Area Surface a light can have. (default 0.05)

• -l max_light_length

  A max limit to the height or width a light can have. (default 0.05)

• -r ratioLight

  a max ratio for light power can have. (default 0.5)

• -n numCuts

  Number of subdivision levers used to generate the lights list. (default is 8)

• -d

  generates a out/debug_variance.png file for debugging light cuts visually. (default is off)