Документация

function meas = helperLidarModel(pos,dim,yaw)
% This function returns the expected bounding box measurement given an
% object's position, dimension, and yaw angle.

% Copyright 2019 The MathWorks, Inc.

% Get x,y and z.
x = pos(1,:);
y = pos(2,:);
z = pos(3,:) - 2; % lidar mounted at height = 2 meters.

% Get spherical measurement.
[az,~,r] = cart2sph(x,y,z);

% Shrink rate
s = 3/50; % 3 meters radial length at 50 meters.
sz = 2/50; % 2 meters height at 50 meters.

% Get length, width and height.
L = dim(1,:);
W = dim(2,:);
H = dim(3,:);

az = az - deg2rad(yaw);

% Shrink length along radial direction.
Lshrink = min(L,abs(s*r.*(cos(az))));
Ls = L - Lshrink;

% Shrink width along radial direction.
Wshrink = min(W,abs(s*r.*(sin(az))));
Ws = W - Wshrink;

% Shrink height.
Hshrink = min(H,sz*r);
Hs = H - Hshrink;

% Measurement is given by a min-max detector hence length and width must be
% projected along x and y.
Lmeas = Ls.*cosd(yaw) + Ws.*sind(yaw);
Wmeas = Ls.*sind(yaw) + Ws.*cosd(yaw);

% Similar shift is for x and y directions.
shiftX = Lshrink.*cosd(yaw) + Wshrink.*sind(yaw);
shiftY = Lshrink.*sind(yaw) + Wshrink.*cosd(yaw);
shiftZ = Hshrink;

% Modeling the affect of box origin offset
x = x - sign(x).*shiftX/2;
y = y - sign(y).*shiftY/2;
z = z + shiftZ/2 + 2;

% Measurement format
meas = [x;y;z;Lmeas;Wmeas;Hs];

end

function [pos,posCov,dim,dimCov,yaw,yawCov] = helperInverseLidarModel(meas,measCov)
% This function returns the position, dimension, yaw using a bounding
% box measurement.

% Copyright 2019 The MathWorks, Inc.

% Shrink rate.
s = 3/50;
sz = 2/50;

% x,y and z of measurement
x = meas(1,:);
y = meas(2,:);
z = meas(3,:);

[az,~,r] = cart2sph(x,y,z);

% Shift x and y position.
Lshrink = abs(s*r.*(cos(az)));
Wshrink = abs(s*r.*(sin(az)));
Hshrink = sz*r;

shiftX = Lshrink;
shiftY = Wshrink;
shiftZ = Hshrink;

x = x + sign(x).*shiftX/2;
y = y + sign(y).*shiftY/2;
z = z + sign(z).*shiftZ/2;

pos = [x;y;z];
posCov = measCov(1:3,1:3,:);

yaw = zeros(1,numel(x),'like',x);
yawCov = ones(1,1,numel(x),'like',x);

% Dimensions are initialized for a standard passenger car with low
% uncertainity.
dim = [4.7;1.8;1.4];
dimCov = 0.01*eye(3);
end

classdef HelperBoundingBoxDetector < matlab.System
    % HelperBoundingBoxDetector A helper class to segment the point cloud
    % into bounding box detections.
    % The step call to the object does the following things:
    %
    % 1. Removes point cloud outside the limits.
    % 2. From the survived point cloud, segments out ground
    % 3. From the obstacle point cloud, forms clusters and puts bounding
    %    box on each cluster.
    
    % Cropping properties
    properties
        XLimits = [-70 70];
        YLimits = [-6 6];
        ZLimits = [-2 10];
    end
   
    % Ground Segmentation Properties
    properties
        GroundMaxDistance = 0.3;
        GroundReferenceVector = [0 0 1];
        GroundMaxAngularDistance = 5;
    end
    
    % Bounding box Segmentation properties
    properties
        SegmentationMinDistance = 1.6;
        MinDetectionsPerCluster = 2;
        MaxZDistanceCluster = 3;
        MinZDistanceCluster = -3;
    end
    
    % Ego vehicle radius to remove ego vehicle point cloud.
    properties
        EgoVehicleRadius = 3;
    end
    
    properties
        MeasurementNoise = blkdiag(eye(3),eye(3));
    end
    
    methods 
        function obj = HelperBoundingBoxDetector(varargin)
            setProperties(obj,nargin,varargin{:})
        end
    end
    
    methods (Access = protected)
        function [bboxDets,obstacleIndices,groundIndices,croppedIndices] = stepImpl(obj,currentPointCloud,time)
            % Crop point cloud
            [pcSurvived,survivedIndices,croppedIndices] = cropPointCloud(currentPointCloud,obj.XLimits,obj.YLimits,obj.ZLimits,obj.EgoVehicleRadius);
            % Remove ground plane
            [pcObstacles,obstacleIndices,groundIndices] = removeGroundPlane(pcSurvived,obj.GroundMaxDistance,obj.GroundReferenceVector,obj.GroundMaxAngularDistance,survivedIndices);
            % Form clusters and get bounding boxes
            detBBoxes = getBoundingBoxes(pcObstacles,obj.SegmentationMinDistance,obj.MinDetectionsPerCluster,obj.MaxZDistanceCluster,obj.MinZDistanceCluster);
            % Assemble detections
            bboxDets = assembleDetections(detBBoxes,obj.MeasurementNoise,time);
        end
    end
end    
    
function detections = assembleDetections(bboxes,measNoise,time)
% This method assembles the detections in objectDetection format.
numBoxes = size(bboxes,2);
detections = cell(numBoxes,1);
for i = 1:numBoxes
    detections{i} = objectDetection(time,cast(bboxes(:,i),'double'),...
        'MeasurementNoise',double(measNoise),'ObjectAttributes',struct);
end
end

function bboxes = getBoundingBoxes(ptCloud,minDistance,minDetsPerCluster,maxZDistance,minZDistance)
    % This method fits bounding boxes on each cluster with some basic
    % rules.
    % Cluster must have atleast minDetsPerCluster points.
    % Its mean z must be between maxZDistance and minZDistance.
    % length, width and height are calculated using min and max from each
    % dimension.
    [labels,numClusters] = pcsegdist(ptCloud,minDistance);
    pointData = ptCloud.Location;
    bboxes = nan(6,numClusters,'like',pointData);
    isValidCluster = false(1,numClusters);
    for i = 1:numClusters
        thisPointData = pointData(labels == i,:);
        meanPoint = mean(thisPointData,1);
        if size(thisPointData,1) > minDetsPerCluster && ...
                meanPoint(3) < maxZDistance && meanPoint(3) > minZDistance
            xMin = min(thisPointData(:,1));
            xMax = max(thisPointData(:,1));
            yMin = min(thisPointData(:,2));
            yMax = max(thisPointData(:,2));
            zMin = min(thisPointData(:,3));
            zMax = max(thisPointData(:,3));
            l = (xMax - xMin);
            w = (yMax - yMin);
            h = (zMax - zMin);
            x = (xMin + xMax)/2;
            y = (yMin + yMax)/2;
            z = (zMin + zMax)/2;
            bboxes(:,i) = [x y z l w h]';
            isValidCluster(i) = l < 20; % max length of 20 meters
        end
    end
    bboxes = bboxes(:,isValidCluster);
end

function [ptCloudOut,obstacleIndices,groundIndices] = removeGroundPlane(ptCloudIn,maxGroundDist,referenceVector,maxAngularDist,currentIndices)
    % This method removes the ground plane from point cloud using
    % pcfitplane.
    [~,groundIndices,outliers] = pcfitplane(ptCloudIn,maxGroundDist,referenceVector,maxAngularDist);
    ptCloudOut = select(ptCloudIn,outliers);
    obstacleIndices = currentIndices(outliers);
    groundIndices = currentIndices(groundIndices);
end

function [ptCloudOut,indices,croppedIndices] = cropPointCloud(ptCloudIn,xLim,yLim,zLim,egoVehicleRadius)
    % This method selects the point cloud within limits and removes the
    % ego vehicle point cloud using findNeighborsInRadius
    locations = ptCloudIn.Location;
    insideX = locations(:,1) < xLim(2) & locations(:,1) > xLim(1);
    insideY = locations(:,2) < yLim(2) & locations(:,2) > yLim(1);
    insideZ = locations(:,3) < zLim(2) & locations(:,3) > zLim(1);
    inside = insideX & insideY & insideZ;
    
    % Remove ego vehicle
    nearIndices = findNeighborsInRadius(ptCloudIn,[0 0 0],egoVehicleRadius);
    nonEgoIndices = true(ptCloudIn.Count,1);
    nonEgoIndices(nearIndices) = false;
    validIndices = inside & nonEgoIndices;
    indices = find(validIndices);
    croppedIndices = find(~validIndices);
    ptCloudOut = select(ptCloudIn,indices);
end

function [detections,obstacleIndices,groundIndices,croppedIndices,...
    confirmedTracks, modelProbs] = mexLidarTracker(ptCloudLocations,time)

persistent detectorModel tracker detectableTracksInput currentNumTracks


if isempty(detectorModel) || isempty(tracker) || isempty(detectableTracksInput) || isempty(currentNumTracks)

    % A bounding box detector model.
    detectorModel = HelperBoundingBoxDetector(...
                    'XLimits',[-50 75],...              % min-max
                    'YLimits',[-5 5],...                % min-max
                    'ZLimits',[-2 5],...                % min-max
                    'SegmentationMinDistance',1.6,...   % minimum Euclidian distance
                    'MinDetectionsPerCluster',1,...     % minimum points per cluster
                    'MeasurementNoise',eye(6),...       % measurement noise in detection report.
                    'GroundMaxDistance',0.3);           % maximum distance of ground points from ground plane
    
    assignmentGate = [10 100]; % Assignment threshold;
    confThreshold = [7 10];    % Confirmation threshold for history logic
    delThreshold = [8 10];     % Deletion threshold for history logic
    Kc = 1e-5;                 % False-alarm rate per unit volume
    
    filterInitFcn = @helperInitIMMFilter;
    
    tracker = trackerJPDA('FilterInitializationFcn',filterInitFcn,...
                      'TrackLogic','History',...
                      'AssignmentThreshold',assignmentGate,...
                      'ClutterDensity',Kc,...
                      'ConfirmationThreshold',confThreshold,...
                      'DeletionThreshold',delThreshold,...
                      'HasDetectableTrackIDsInput',true,...
                      'InitializationThreshold',0,...
                      'MaxNumTracks',30);
    
    detectableTracksInput = zeros(tracker.MaxNumTracks,2);
    
    currentNumTracks = 0;
end

ptCloud = pointCloud(ptCloudLocations);

% Detector model
[detections,obstacleIndices,groundIndices,croppedIndices] = detectorModel(ptCloud,time);

% Call tracker
[confirmedTracks,~,allTracks] = tracker(detections,time,detectableTracksInput(1:currentNumTracks,:));
% Update the detectability input
currentNumTracks = numel(allTracks);
detectableTracksInput(1:currentNumTracks,:) = helperCalcDetectability(allTracks,[1 3 6]);    

% Get model probabilities
modelProbs = zeros(2,numel(confirmedTracks));
if isLocked(tracker)
    for k = 1:numel(confirmedTracks)
        c1 = getTrackFilterProperties(tracker,confirmedTracks(k).TrackID,'ModelProbabilities');
        probs = c1{1};
        modelProbs(1,k) = probs(1);
        modelProbs(2,k) = probs(2);
    end
end

end

function detectableTracksInput = helperCalcDetectability(tracks,posIndices)
% This is a helper function to calculate the detection probability of
% tracks for the lidar tracking example. It may be removed in a future
% release.

% Copyright 2019 The MathWorks, Inc.

% The bounding box detector has low probability of segmenting point clouds
% into bounding boxes are distances greater than 40 meters. This function
% models this effect using a state-dependent probability of detection for
% each tracker. After a maximum range, the Pd is set to a high value to
% enable deletion of track at a faster rate.
if isempty(tracks)
    detectableTracksInput = zeros(0,2);
    return;
end
rMax = 75;
rAmbig = 40;
stateSize = numel(tracks(1).State);
posSelector = zeros(3,stateSize);
posSelector(1,posIndices(1)) = 1;
posSelector(2,posIndices(2)) = 1;
posSelector(3,posIndices(3)) = 1;
pos = getTrackPositions(tracks,posSelector);
if coder.target('MATLAB')
    trackIDs = [tracks.TrackID];
else
    trackIDs = zeros(1,numel(tracks),'uint32');
    for i = 1:numel(tracks)
        trackIDs(i) = tracks(i).TrackID;
    end
end
[~,~,r] = cart2sph(pos(:,1),pos(:,2),pos(:,3));
probDetection = 0.9*ones(numel(tracks),1);
probDetection(r > rAmbig) = 0.4;
probDetection(r > rMax) = 0.99;
detectableTracksInput = [double(trackIDs(:)) probDetection(:)];
end