1 files changed, 80 insertions, 0 deletions
diff --git a/samples/ObjectDetection/src/SSDResultDecoder.cpp b/samples/ObjectDetection/src/SSDResultDecoder.cpp
new file mode 100644
index 0000000000..a3319212e5
--- /dev/null
+++ b/samples/ObjectDetection/src/SSDResultDecoder.cpp
@@ -0,0 +1,80 @@
+//
+// Copyright © 2020 Arm Ltd and Contributors. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#include "SSDResultDecoder.hpp"
+
+#include <cassert>
+#include <algorithm>
+#include <cmath>
+#include <stdexcept>
+namespace od
+{
+
+DetectedObjects SSDResultDecoder::Decode(const InferenceResults& networkResults,
+    const Size& outputFrameSize,
+    const Size& resizedFrameSize,
+    const std::vector<std::string>& labels)
+{
+    // SSD network outputs 4 tensors: bounding boxes, labels, probabilities, number of detections.
+    if (networkResults.size() != 4)
+    {
+        throw std::runtime_error("Number of outputs from SSD model doesn't equal 4");
+    }
+
+    DetectedObjects detectedObjects;
+    const int numDetections = static_cast<int>(std::lround(networkResults[3][0]));
+
+    double longEdgeInput = std::max(resizedFrameSize.m_Width, resizedFrameSize.m_Height);
+    double longEdgeOutput = std::max(outputFrameSize.m_Width, outputFrameSize.m_Height);
+    const double resizeFactor = longEdgeOutput/longEdgeInput;
+
+    for (int i=0; i<numDetections; ++i)
+    {
+        if (networkResults[2][i] > m_objectThreshold)
+        {
+            DetectedObject detectedObject;
+            detectedObject.SetScore(networkResults[2][i]);
+            auto classId = std::lround(networkResults[1][i]);
+
+            if (classId < labels.size())
+            {
+                detectedObject.SetLabel(labels[classId]);
+            }
+            else
+            {
+                detectedObject.SetLabel(std::to_string(classId));
+            }
+            detectedObject.SetId(classId);
+
+            // Convert SSD bbox outputs (ratios of image size) to pixel values.
+            double topLeftY = networkResults[0][i*4 + 0] * resizedFrameSize.m_Height;
+            double topLeftX = networkResults[0][i*4 + 1] * resizedFrameSize.m_Width;
+            double botRightY = networkResults[0][i*4 + 2] * resizedFrameSize.m_Height;
+            double botRightX = networkResults[0][i*4 + 3] * resizedFrameSize.m_Width;
+
+            // Scale the coordinates to output frame size.
+            topLeftY *= resizeFactor;
+            topLeftX *= resizeFactor;
+            botRightY *= resizeFactor;
+            botRightX *= resizeFactor;
+
+            assert(botRightX > topLeftX);
+            assert(botRightY > topLeftY);
+
+            // Internal BoundingBox stores box top left x,y and width, height.
+            detectedObject.SetBoundingBox({static_cast<int>(std::round(topLeftX)),
+                                           static_cast<int>(std::round(topLeftY)),
+                                           static_cast<unsigned int>(botRightX - topLeftX),
+                                           static_cast<unsigned int>(botRightY - topLeftY)});
+
+            detectedObjects.emplace_back(detectedObject);
+        }
+    }
+    return detectedObjects;
+}
+
+SSDResultDecoder::SSDResultDecoder(float ObjectThreshold) : m_objectThreshold(ObjectThreshold) {}
+
+}// namespace od
+\ No newline at end of file