How can I filter images and improve the depth quality for Intel® RealSense™ D415?

How can I make sure that I don't have noise on my depth image and how can I upgrade the quality on Intel® RealSense™ D415?

Please check the Post-Processing example, which adds additional filters over your depth stream in order to make the depth measurements more accurate.
The filters used are:

• Decimation (Intelligently reduces the resolution of a depth frame)
• Disparity (Performs transformation between depth and disparity domains and it is applicable for stereo-based depth sensors only)
• Spatial (Applies edge-preserving smoothing of depth data.)
• Temporal (Filters depth data by looking into previous frames.) 

Another way to improve the depth accuracy is to use texture for the environment.

In order to make sure that you are using the RealSense camera at it's best performances, you can check the Best-Known-Methods for Tuning Intel® RealSense™ white paper