The reference picture was taken from the "Star Trek: TNG Interactive Technical Manual" VR files. I believe these were produced with a camera that took three dimensional pictures of the sets at different locations. I've noticed while viewing these files that the lens on the special camera probably had fish-eye lenses, which may explain the dimensional difference.
When those special cameras were used to record the sets of TNG, it also appears that the lighting was adjusted for the occasion to give a brighter appearance, and due to the computer video recording capabilities of the time, the color has a yellowish tint all around.
What I do is use the three dimensional VR files as a reference when making the architecture of each area, and then use screencaps of TNG episodes for lighting and color references.
Either way, I continually check my work against the actual set schematics, so the dimensions should be fairly close to the actual set dimensions, give or take a few inches.