Simple Python script to convert a bump map to a normal map. Not optimized for performance.
- Python 3
- numpy
- opencv-python
python bumptonormalmap.py <path to bump map> <strength>
# <path to bump map> : string -> path to the input image (the bump map, i.e. the height map)
#
# <strength> : float > 0 -> "strength" of the normal map
# results in smoother (strength -> 0) or sharper (strength -> \infty) features
# strength = 1 (recommended to start with)
# strength = 2 (more defined features)
# strength = 10 (really strong normal mapping effect...)
# just experiment a little bit :)# Uses horizontal and vertical sobel filters (https://docs.opencv.org/3.4/d2/d2c/tutorial_sobel_derivatives.html)
# to detect edges to determine the gradients in horizontal and vertical direction respectively.
#
# GX = [ -1 0 1] = [1]
# [ -2 0 2] [2] * [-1 0 1]
# [ -1 0 1] [1]
#
# GY = [ -1 -2 -1] = [-1]
# [ 0 0 0] [ 0] * [1 2 1]
# [ 1 2 1] [ 1]
#
# The sobel filter is separable which allows to compute two one-dimensional convolutions instead of one two-dimensional
# (accelerates computation).
#
# The normals are computed from the gradients in horizontal (dx) and vertical direction (dy) as follows:
# normal = normalize(vec3(dx, dy, 1.0 / strength))
#
# Note that the normals are transformed from [-1,1] space to [0,1] space (normal * vec3(0.5) + vec3(0.5)).
# Remember to undo the transformation (vec3(2.0) * normal - vec3(1.0)) when reading the normals from the normal map.The bump map is taken from the LPS Head model. The complete model including the bump map can be downloaded from https://casual-effects.com/data/.
python bumptonormalmap.py example/bump_map.png 2
