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Original question:

IWR6843ISK-ODS: target object TLV in 3D people counting lab

IWR6843ISK-ODS: number of target object is different from the number of valid targets in target index in 3D people counting lab

Kai Yang1
Expert 1400 points
Part Number: IWR6843ISK-ODS


Hi

I am having an issue in 3D people counting lab now. At certain frame, Target List includes 2 targets (ID: 0 and 1) but the Target Index only includes target ID 1. Have you ever seen similar issue? I am using industrial toolbox 4.3.2.

Thanks!

Kai

  • 0
    TI__Mastermind 30405 points

    Hi Kai,

    The tracker runs one frame behind the point cloud (i.e. list of detected objects) which means that the list of detected objects is for frame N while the Target list and the target Index list are both for frame N-1. 

    As defined in the 3D people counting demo user guide, each entry in the target Index TLV represents the target to which this point was associated in frame N-1. Therefore, you can have the number of detected objects (point cloud) in frame N more than the number of target Index since these lists are from two different frames.

    Target Index TLV

    Type: TARGET_INDEX Size: sizeof (tlvHeaderStruct) + numberOfPoints (NOTE: here the number of points are for frame n-1)

    Each Target List TLV consists of an array of target IDs. A targetID at index i is the target to which point i of the previous frame's point cloud was associated. Valid IDs range from 0-249.

    Regards

    -Nitin

     

  • 0 in reply to Nitin Sakhuja
    Expert 1400 points

    Hi Nitin

    Thanks for your quick reply!

    I totally understand what you described above. My question is as follows.

    At certain frame, the Target List TLV includes 2 targets whose IDs are 0 and 1. Therefore, I should expect to see target ID 0 and 1 in the Target Index TLV as well but I only see target ID 1 in addition to target IDs greater than 249. Why is target ID 0 not included in the Target Index TLV?

    Thanks!

    Kai 

  • 0 in reply to Kai Yang1
    TI__Mastermind 30405 points

    Hi Kai,

    Please allow me a couple of days to dig a little more on this and get back to you.

    Regards

    -Nitin

  • 0 in reply to Nitin Sakhuja
    TI__Mastermind 30405 points

    Hi Kai,

    At certain frame, the Target List TLV includes 2 targets whose IDs are 0 and 1. Therefore, I should expect to see target ID 0 and 1 in the Target Index TLV as well but I only see target ID 1 in addition to target IDs greater than 249. Why is target ID 0 not included in the Target Index TLV?

    For a given index i, If target_index[i] > 249, it means that, that particular point in the point Cloud TLV, i.e. pointCloud[i] was not attached to any target Id due to one of the following reasons as given in the demo user guide:


    So the condition you see above is not an error and not all the points always map to a known target due to one of the above reasons.

    Hope this clarifies the doubt but please get back if you have more questions.

    Regards

    -Nitin