| 13 | { |
| 14 | |
| 15 | DetectedObjects SSDResultDecoder::Decode(const common::InferenceResults<float>& networkResults, |
| 16 | const common::Size& outputFrameSize, |
| 17 | const common::Size& resizedFrameSize, |
| 18 | const std::vector<std::string>& labels) |
| 19 | { |
| 20 | // SSD network outputs 4 tensors: bounding boxes, labels, probabilities, number of detections. |
| 21 | if (networkResults.size() != 4) |
| 22 | { |
| 23 | throw std::runtime_error("Number of outputs from SSD model doesn't equal 4"); |
| 24 | } |
| 25 | |
| 26 | DetectedObjects detectedObjects; |
| 27 | const int numDetections = static_cast<int>(std::lround(networkResults[3][0])); |
| 28 | |
| 29 | double longEdgeInput = std::max(resizedFrameSize.m_Width, resizedFrameSize.m_Height); |
| 30 | double longEdgeOutput = std::max(outputFrameSize.m_Width, outputFrameSize.m_Height); |
| 31 | const double resizeFactor = longEdgeOutput/longEdgeInput; |
| 32 | |
| 33 | for (int i=0; i<numDetections; ++i) |
| 34 | { |
| 35 | if (networkResults[2][i] > m_objectThreshold) |
| 36 | { |
| 37 | DetectedObject detectedObject; |
| 38 | detectedObject.SetScore(networkResults[2][i]); |
| 39 | auto classId = std::lround(networkResults[1][i]); |
| 40 | |
| 41 | if (classId < labels.size()) |
| 42 | { |
| 43 | detectedObject.SetLabel(labels[classId]); |
| 44 | } |
| 45 | else |
| 46 | { |
| 47 | detectedObject.SetLabel(std::to_string(classId)); |
| 48 | } |
| 49 | detectedObject.SetId(classId); |
| 50 | |
| 51 | // Convert SSD bbox outputs (ratios of image size) to pixel values. |
| 52 | double topLeftY = networkResults[0][i*4 + 0] * resizedFrameSize.m_Height; |
| 53 | double topLeftX = networkResults[0][i*4 + 1] * resizedFrameSize.m_Width; |
| 54 | double botRightY = networkResults[0][i*4 + 2] * resizedFrameSize.m_Height; |
| 55 | double botRightX = networkResults[0][i*4 + 3] * resizedFrameSize.m_Width; |
| 56 | |
| 57 | // Scale the coordinates to output frame size. |
| 58 | topLeftY *= resizeFactor; |
| 59 | topLeftX *= resizeFactor; |
| 60 | botRightY *= resizeFactor; |
| 61 | botRightX *= resizeFactor; |
| 62 | |
| 63 | assert(botRightX > topLeftX); |
| 64 | assert(botRightY > topLeftY); |
| 65 | |
| 66 | // Internal BoundingBox stores box top left x,y and width, height. |
| 67 | detectedObject.SetBoundingBox({static_cast<int>(std::round(topLeftX)), |
| 68 | static_cast<int>(std::round(topLeftY)), |
| 69 | static_cast<unsigned int>(botRightX - topLeftX), |
| 70 | static_cast<unsigned int>(botRightY - topLeftY)}); |
| 71 | |
| 72 | detectedObjects.emplace_back(detectedObject); |