MartyG-RealSense
commented
3 years ago Hi @AJMena There are some pre-made options available for measuring between two points. It can be done with the Measure option in the 3D point cloud mode of the RealSense Viewer program (dragging a line with the mouse between two points on the point cloud), or with the SDK's rs-measure C++ example program.
https://github.com/IntelRealSense/librealsense/tree/master/examples/measure
rs-measure takes the approach of aligning color to depth instead of the most commonly used alignment method of depth to color. Developing a RealSense measuring application based on rs-measure may enable you to not have to use an external solution such as CloudCompare.
I have a recollection that one of the reasons for choosing color to depth in that example program though was simply to demonstrate how to perform color to depth alignment in the SDK, and a Python conversion of rs-measure by a RealSense user used depth to color alignment instead. So the difference between choosing one method or the other may be minimal, as your own tests suggested.
The alignment process aligns the data to the field of view (FOV) size of the source that you are aligning to. For example, depth to color alignment aligns the depth to the color FOV size. On the D435 and D435i models, the color FOV is smaller than the depth FOV, which may result in depth coordinates on the outer regions of the image being excluded from the image after alignment. The rs-align example explains these principles in its opening paragraph.
https://github.com/IntelRealSense/librealsense/tree/master/examples/align
If you are using the Windows version of the SDK, a pre-built executable version of rs-measure that can be launched with a double-leftclick can be found in the SDK's Tools folder. An easy way to find this folder is to right-click on the RealSense Viewer's launch sortcut icon on the Windows desktop and select the Open file location menu option.
AJMena
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Issue Description
We are trying to measure the distances in 3D between some objects. We calculate the 3D coordinates of the points, export them, and then measure in CloudCompare (an external program). We calculate the 3D coordinates like its described in this article: https://github.com/IntelRealSense/librealsense/wiki/Projection-in-RealSense-SDK-2.0#processing-blocks-helpers We are wondering if we must align the frames to depth, to color or not align before calculating the points. The aligned process is described in the article too. We did some tests. We exported the point cloud without using align (default), using align to depth and using align to color. The results are slightly different. The color of the points is moved between the default and align to depth but the points are in the same coordinates and in align to depth some points do not have color. The points are translated between the default and align to color result.
So, how should we do it?