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Feat(Tracker): Allow for custom distance functions #4

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Merged
vsaw merged 1 commit into from
Aug 11, 2020
Merged

Feat(Tracker): Allow for custom distance functions #4

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17 changes: 17 additions & 0 deletions spec/Tracker.spec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -84,4 +84,21 @@ describe('Tracker', function () {
expect(Tracker.getJSONOfTrackedItems()[0].id).toBe(0);
});
});

describe('custom distance function', function() {
var distanceSpy;
beforeEach(function() {
distanceSpy = jasmine.createSpy('distance spy', Tracker.iouDistance);

Tracker.reset();
Tracker.setParams({ distanceFunc: distanceSpy });
detections.forEach((frame, frameNb) => {
Tracker.updateTrackedItemsWithNewFrame(frame, frameNb);
});
});

it('called the custom distance', function() {
expect(distanceSpy).toHaveBeenCalled();
});
});
});
44 changes: 24 additions & 20 deletions tracker.js
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,23 @@ var iouAreas = require('./utils').iouAreas

var DEBUG_MODE = false;

// Distance function
const iouDistance = function(item1, item2) {
// IOU distance, between 0 and 1
// The smaller the less overlap
var iou = iouAreas(item1, item2);

// Invert this as the KDTREESEARCH is looking for the smaller value
var distance = 1 - iou;

// If the overlap is iou < 0.95, exclude value
if(distance > (1 - params.iouLimit)) {
distance = KDTREESEARCH_LIMIT + 1;
}

return distance;
}

const params = {
// DEFAULT_UNMATCHEDFRAMES_TOLERANCE
// This the number of frame we wait when an object isn't matched before considering it gone
Expand All @@ -17,7 +34,9 @@ const params = {
// Setting this to false ensures the object will stick around at least
// unMatchedFramesTolerance frames, even if they could neven be matched in
// subsequent frames.
fastDelete: true
fastDelete: true,
// The function to use to determine the distance between to detected objects
distanceFunc: iouDistance
}

// A dictionary of itemTracked currently tracked
Expand All @@ -37,33 +56,18 @@ var keepAllHistoryInMemory = false;
var KDTREESEARCH_LIMIT = 10000;


// Distance function
const computeDistance = function(item1, item2) {
// IOU distance, between 0 and 1
// The smaller the less overlap
var iou = iouAreas(item1, item2);

// Invert this as the KDTREESEARCH is looking for the smaller value
var distance = 1 - iou;

// If the overlap is iou < 0.95, exclude value
if(distance > (1 - params.iouLimit)) {
distance = KDTREESEARCH_LIMIT + 1;
}

return distance;
}

exports.computeDistance = computeDistance;
exports.computeDistance = iouDistance;

exports.updateTrackedItemsWithNewFrame = function(detectionsOfThisFrame, frameNb) {

// A kd-tree containing all the itemtracked
// Need to rebuild on each frame, because itemTracked positions have changed
var treeItemsTracked = new kdTree(Array.from(mapOfItemsTracked.values()), computeDistance, ["x", "y", "w", "h"]);
var treeItemsTracked = new kdTree(Array.from(mapOfItemsTracked.values()), params.distanceFunc, ["x", "y", "w", "h"]);

// Contruct a kd tree for the detections of this frame
var treeDetectionsOfThisFrame = new kdTree(detectionsOfThisFrame, computeDistance, ["x", "y", "w", "h"]);
var treeDetectionsOfThisFrame = new kdTree(detectionsOfThisFrame, params.distanceFunc, ["x", "y", "w", "h"]);

// SCENARIO 1: itemsTracked map is empty
if(mapOfItemsTracked.size === 0) {
Expand Down Expand Up @@ -187,7 +191,7 @@ exports.updateTrackedItemsWithNewFrame = function(detectionsOfThisFrame, frameNb
// to existing trackedItems this avoids adding some double match of YOLO and bring down drasticly reassignments
if(mapOfItemsTracked.size > 0) { // Safety check to see if we still have object tracked (could have been deleted previously)
// Rebuild tracked item tree to take in account the new positions
treeItemsTracked = new kdTree(Array.from(mapOfItemsTracked.values()), computeDistance, ["x", "y", "w", "h"]);
treeItemsTracked = new kdTree(Array.from(mapOfItemsTracked.values()), params.distanceFunc, ["x", "y", "w", "h"]);
// console.log(`Nb new items Unmatched : ${matchedList.filter((isMatched) => isMatched === false).length}`)
matchedList.forEach(function(matched, index) {
// Iterate through unmatched new detections
Expand Down