Point Cloud Assembler

This tutorial demonstrates how to accumulate dwLidarDecodedPacketEx to a lidar spin point cloud.

Create point cloud assembler module:

dwPointCloudAssemblerParams params{};
 
// Enable GPU accumulation
params.enableCuda = true;
 
// Set number of point cloud layers to 3, one per lidar return
params.mapping.numLayers = 3;
params.mapping.layerType[0] = DW_LIDAR_RETURN_TYPE_STRONGEST;
params.mapping.layerType[1] = DW_LIDAR_RETURN_TYPE_FIRST;
params.mapping.layerType[2] = DW_LIDAR_RETURN_TYPE_LAST;
 
// Set auxiliary channels mapping, one channel per aux data array
params.mapping.numAuxChannels = 3;
params.mapping.auxType[0] = DW_LIDAR_AUX_DATA_TYPE_TIME;
params.mapping.auxType[1] = DW_LIDAR_AUX_DATA_TYPE_LINEID;
params.mapping.auxType[2] = DW_LIDAR_AUX_DATA_TYPE_NOISELEVEL;
 
// Get properties of a lidar sensor
dwLidarProperties lidarProps{};
dwSensorLidar_getProperties(&lidarProps, sensor);
 
dwPointCloudAssemblerHandle_t assembler{};
dwPointCloudAssembler_initialize(&assembler, &params, &lidarProps, context);

Create output point cloud and bind it to assembler.

// Get number of available lidar returns
uint32_t const numAvailableReturns = lidarProps.availableReturns != DW_LIDAR_RETURN_TYPE_ANY ? static_cast<uint32_t>(std::bitset<32U>(lidarProps.availableReturns).count()) : 1U;
 
// Get number of points in single return
uint32_t const pointsPerLayer = lidarProps.pointsPerSpin / numAvailableReturns;
 
// Array containing aux channel element sizes
uint32_t const auxChannelElementSizes[] = {
                                            sizeof(dwTime_t),  // time element size
                                            sizeof(uint16_t),  // lineId element size
                                            sizeof(float32_t)  // noise level element size
                                          };
 
// Create point cloud
dwPointCloud outputPointCloud{};
dwPointCloud_create(&outputPointCloud,          // output point cloud
                    DW_POINTCLOUD_FORMAT_XYZI,  // format of a point, xyzi of rthi
                    DW_MEMORY_TYPE_CUDA,        // memory type, CUDA or CPU
                    pointsPerLayer,             // maximum number of points in single lidar return 
                    3U,                         // number of requested returns
                    auxChannelElementSizes,     // size of aux channel elements 
                    3U);                        // number of auxiliary channels
 
// Bind created point cloud
dwPointCloudAssembler_bindOutput(&outputPointCloud, assembler);
 
// Set CUDA stream
dwPointCloudAssembler_setCUDAStream(stream, assembler);

To continuously collect the decoded lidar packet until it reaches the scanComplete flag:

bool hasFullSpinReady = false;
dwPointCloudAssembler_isReady(&hasFullSpinReady, assembler);
 
while (!hasFullSpinReady)
{
    // get decoded lidar packet
    dwSensorLidar_readPacektEx(&lidarPacket, sensor);
 
    // add packet to assembler
    dwPointCloudAssembler_addLidarPacket(lidarPacket, assembler);
 
    // update complete flag
    dwPointCloudAssembler_isReady(&hasFullSpinReady, assembler);
}
 
// Assemble the data
dwPointCloudAssembler_process(assembler);
 
// use `outputPointCloud` for other tasks
......

Release the module:

dwPointCloudAssembler_release(assembler);
dwPointCloud_destroy(&outputPointCloud);