PhotometricStereo

OpenCV scripts for generating normalMaps using photometric stereo technique

Dependencies

• OpenCV
• OpenCV(python bindings)

Uses

For a particular art peice choose 3 photos under different lighting conditions where the camera and subject do not move (are aligned)

Place them in a folder with a name of your choosing, and label the images (_1.jpg, _2.jpg, _3.jpg)

Steps should be done in the order as followed or based on your discretion

Example

<img src="./Examples/_1.jpg" width="30%"> <img src="./Examples/_2.jpg" width="30%"> <img src="./Examples/_3.jpg" width="30%">

3 sources images subject and camera position are constant light position varies and positions are unknown

<img src="./Examples/final_1.jpg" width="30%"> <img src="./Examples/final_2.jpg" width="30%"> <img src="./Examples/final_3.jpg" width="30%">

Peform affine adjustments and crop for straight images

<img src="./Examples/demonew.gif" width="50%">

Visualization of estimated light positions

<img src="./Examples/normal_20_500.jpg" width="40%"> <img src="./Examples/albedo.jpg" width="40%">

Generated Normal map along with albedo map ready to use

<img src="./Examples/demo3.gif" width="40%"> <img src="./Examples/demo2.gif" width="40%">

Map in use via A-FRAME(three.js)

Albedo

./albedo [foldername]/

computes and albedo map for the subject by computing pixel averages across the 3 images

Perspective Transform

python transform.py [foldername]/

used to straigten the subject will openup window were you can click on 4 corners for transform click bottom left, top left, top right, bottom right hit [esc]

Crop

python crop.py [foldername]/

Crop to isolate subject opens up window to draw a rectangle, from top left to bottom right of subject hit [esc]

Compute Normal

./normal [foldername]/ [threshold](int) [iterations](int)

Computes normal map Threshold -> ignores sections were the grayscaled image value is below a certain intensity (used to discard shadows) Iterations -> number of iterations to run for simulated annealing, usually 200, but ranges can be from 500-7000