IWR6843ISK-ODS: Data from Overhead Mount Vehicle Occupancy Decection using IWR6843

user6452370

Part Number: IWR6843ISK-ODS
Other Parts Discussed in Thread: IWR6843

Hello,

We are trying to understand data we recorded while running Overhead Mount Vehicle Occupancy Detection using IWR6843. We were able to get fHist_XXX.mat files, but we need help understanding the structure of the point cloud data and how to convert range, azimuth, and elevation to meters.

Q1. What is the correct structure of the pointCloud data? The User Guide states that there are 5 columns, as pasted below. However, I do not think this is correct because I read somewhere in this QA forum that doppler should always be 0 but the numbers in the 4th column are zero (if the data is structured as follows, zeros should be in the 3rd column).

pointStruct = struct(...
'elevation', {'int8_t', 1}, ... % Elevation in radians
'azimuth', {'int8_t', 1}, ... % Azimuth, in radians
'doppler', {'int16_t', 2}, ... % Doppler, in m/s
'range', {'uint16_t', 2}, ... % Range, in meters
'snr', {'uint16_t', 2}); % SNR, ratio

I have mixed&matched numbers and think that the correct structure is as follows. Can someone verify?

pointStruct = struct(...
'elevation', {'int8_t', 1}, ... % Elevation in radians
'range', {'uint16_t', 2}, ... % Range, in meters
'azimuth', {'int8_t', 1}, ... % Azimuth, in radians
'doppler', {'int16_t', 2}, ... % Doppler, in m/s
'snr', {'uint16_t', 2}); % SNR, ratio

Q2. Also, are the units for elevation and range really in radians? I have compared the results on GUI and the data in mat file, and to me, it seems like elevation and range are in meters.

---Data from Overhead Mount Vehicle Occupancy Decection.zip

I am attaching the original mat file, a csv file of pointCloud data at frame 144 that I have converted from the mat file (a random frame for comparison), and a screenshot of GUI at frame 144 as well. If anyone can help me, that would be very helpful.

Thank you.

over 4 years ago

0 Former Member over 4 years ago

Hello,

There are a couple of issues with the replay feature of the GUI. This will be fixed in the next toolbox. Please replace this file in the GUI:

/cfs-file/__key/communityserver-discussions-components-files/1023/overhead_5F00_vod_5F00_visualizer.zip

1) For the data rows 1-5 in pointCloud is

1.range,

2. azimuth angle (rad)

3. elevation angle (rad)

4. doppler (always 0)

5. SNR

This is assigned to point3D which has row 1-4 with

1. x

2. y

3. z

4. SNR

Amanda

0 Former Member over 4 years ago in reply to Former Member

Code snippet doing the above assignment and parsing of fhist

            if(numOutputPoints)
                pointCloud = fHist(frameNum).pointCloud;
                range = pointCloud(1,:);
                azim  = pointCloud(2,:);
                elev  = pointCloud(3,:);           
                point3D = [range.*cos(elev).*sin(azim); range.*sin(elev); -range.*cos(elev).*cos(azim)];
                point3D(3,:) = point3D(3,:) + sensor.height;
                point3D(4,:)=pointCloud(5,:);
            end

0 user6452370 over 4 years ago in reply to Former Member

Prodigy 30 points

Hi, Amanda. Thank you so much for your reply.

I am sorry but we don't have MATLAB, so can you please send us "overhead_vod_visualizer.exe" (in an .exe format, instead of .m format)?

0 user6452370 over 4 years ago in reply to user6452370

Prodigy 30 points

Hi, Amanda.

We were able to get MATLAB and understand the source code you provided.
Thank you so much.

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IWR6843ISK-ODS: Data from Overhead Mount Vehicle Occupancy Decection using IWR6843