how does light effect depth from camera !!

edit

The Realsense is a stereo camera that computes depth based on the two IR cameras on a onboard ASIC . It additionally illuminates the scene with an IR pattern to add structure for the stereo matching. This allows use indoor and outdoor, but within the limits of physics of course.

There are different setting presets available that provide different trade-offs between speckles/noise and depth image density. You can test those with the example programs that come with librealsense.

If for your application both the scene and sensor are static you could also compute the depth image yourself, possibly taking multiple exposures etc., but that is pretty involved.