Hi everyone,
I was able to generate capture the depth of a scene around a viewer location and generate a flat rendering of this scene after using spherical coordinates to sample a previously generated cubemap containing the depth information of a scene (see link for more information on my earlier message and solution posted on this forum).
The result was the resulting image,
which at a first glance looks exactly what I was after. However, when this image (containing depths) is differentiated numerically in both the vertical and horizontal direction respectively, we get some artifacts,
You can see at the bottom how it appears to pick up the seams of the cubemap. These will be more or less obvious depending on the viewpoint location. Before sampling the cubemap, I made sure that
glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS) was included when sampling the cubemap.Couple of comments/questions:
It is clear that whenever I am getting more than two cubemap faces (always including bottom or Y- face), sampling is not smooth as opposed to when I am sampling across the cubemap faces where such discontinuity does not appear to be occurring. In trying to figure out how to resolve this,… I read the following section of the Opengl 4.6 Core Profile document .
8.13.1 Seamless Cube Map Filtering
Seamless cube map filtering is enabled or disabled by calling Enable or Disable
with target TEXTURE_CUBE_MAP_SEAMLESS.
When seamless cube map filtering is disabled, the new s t is used to find a
texture value in the determined face’s two-dimensional image using the rules
in sections 8.14 through 8.15.
When seamless cube map filtering is enabled, the rules for texel selection in
sections 8.14 through 8.15 are modified so that texture wrap modes are ignored.
Instead,
• If NEAREST filtering is done within a miplevel, always apply wrap mode
CLAMP_TO_EDGE.
• If LINEAR filtering is done within a miplevel, always apply wrap mode
CLAMP_TO_BORDER. Then,
– If a texture sample location would lie in the texture border in either u or v, instead select the corresponding texel from the appropriate neighboring face.
– If a texture sample location would lie in the texture border in both u and v (in one of the corners of the cube), there is no unique neighboring face from which to extract one texel. The recommended method to generate this texel is to average the values of the three available samples. However, implementations are free to construct this fourth texel in another way, so long as, when the three available samples have the same value, this texel also has that value.
The required state is one bit indicating whether seamless cube map filtering is enabled or disabled. Initially, it is disabled.
I Made sure that my when creating my cubemap wrap mode was set to CLAMP_TO_BORDER but this did not change anything. If I understand correctly, the above paragraph mentions the possibility of averaging the values found in three cubemap faces but I am uncertain whether a) this is already beeing done? OR b) if not, how this can be achieved?
Any ideas, guidance or comments are very welcome.
M.