.tflite model for SSD MobileNet v3 Object Detection Does Not Make Detections

[SamuelJakes]

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System information

• What is the top-level directory of the model you are using: SSD Mobilenet V3, large and small, downloaded from https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/detection_model_zoo.md
• Have I written custom code (as opposed to using a stock example script provided in TensorFlow): I'm modifying sample code to get it to work with mobilenet_v3 instead of mobilenet_v1 given here: https://github.com/tensorflow/examples/tree/master/lite/examples/object_detection/android
• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Linux Ubuntu 18.04
• TensorFlow installed from (source or binary): pip3 binary
• TensorFlow version (use command below): v1.12
• Bazel version (if compiling from source): N/A
• CUDA/cuDNN version: N/A
• GPU model and memory: N/A
• Exact command to reproduce: N/A

Describe the problem

I can get other .tflite models to work for object detection, such as the default ssd_mobilenet_v1, but the ssd_mobilenet_v3 model won't produce a prediction confidence any larger than 10^-15, i.e., it never makes predictions. Unless I'm missing some fundamental difference between the way ssd_mobilenet_v3 takes input data ssd_mobilenet_v1 takes input data (which is possible, but I can't find any documentation that indicates this) then it seems like the ssd_mobilenet_v3 just doesn't work for whatever reason.

Source code / logs

Here is a summary of the code I'm using to feed the model input data:

//Note that the model takes a 320 x 320 image.

//Get image data as integer values
private int[] intValues;
intValues = new int[320 * 320];

private Bitmap croppedBitmap = null;
croppedBitmap = Bitmap.createBitmap(320, 320, Config.ARGB_8888);
croppedBitmap.getPixels(intValues, 0, bitmap.getWidth(), 0, 0, bitmap.getWidth(), bitmap.getHeight());

//create ByteBuffer as input for running ssd_mobilenet_v3
private ByteBuffer imgData;
imgData = ByteBuffer.allocateDirect(320 * 320 * 3);
imgData.order(ByteOrder.nativeOrder());

//Fill Bytebuffer
//Note that & 0xFF is for just getting the last 8 bits, for converting to RGB values here
imgData.rewind();
for (int i = 0; i < inputSize; ++i) {
  for (int j = 0; j < inputSize; ++j) {
    int pixelValue = intValues[i * inputSize + j];
    // Quantized model
    imgData.put((byte) ((pixelValue >> 16) & 0xFF));
    imgData.put((byte) ((pixelValue >> 8) & 0xFF));
    imgData.put((byte) (pixelValue & 0xFF));
  }
}

// Set up output buffers
private float[][][] output0;
private float[][][][] output1;
output0 = new float[1][2034][91];
output1 = new float[1][2034][1][4];

//Create input HashMap and run the model
Object[] inputArray = {imgData};
Map<Integer, Object> outputMap = new HashMap<>();
outputMap.put(0, output0);
outputMap.put(1, output1);
tfLite.runForMultipleInputsOutputs(inputArray, outputMap);

//Examine Confidences
for (int i = 0; i < 2034; i++) {
  for (int j = 0; j < 91; j++) {
    System.out.println(output0[0][i][j]);
  }
}

[skulhare]

Hi, did you get any update on this? I am also facing the same issue. Thanks

[idenc]

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