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How to deploy trained Faster RCNN object detector in Simulink

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Kindly assist me on how to use my trained Faster RCNN object detector in Simulink.
I have trained a Faster RCNN object detector in matlab, however, I am having difficulty in getting resources and way point on how to use it in simulink.
I humbly need urgent response.

Answers (2)

Patel Mounika
Patel Mounika on 22 Feb 2019
Edited: Patel Mounika on 22 Feb 2019
There is no direct way to use Faster RCNN object detector in Simulink but instead you can use coder.extrinsic to wrap the call to object detector inside a MATLAB Function block.
You can refer to below link to know more about coder.extrinsic:https://www.mathworks.com/help/fixedpoint/ref/coder.extrinsic.html
For example, the MATLAB Function block can be defined as follows:
function[bboxes,scores]= function(I)
coder.extrinsic('detect');
coder.extrinsic('evalin');
[bboxes,scores] = evalin('base','detect(detector,I)'); % detector is fasterRCNNObjectDetector and I is image.
Hope this helps.
  2 Comments
HAMMED OBASEKORE
HAMMED OBASEKORE on 22 Feb 2019
Thanks so much for the response. It came in when I almost gave up on it.
However, I actualy did that, but, I received errors when loading the detector (fasterRCNNObjectDetector) from the .mat file I saved.
function y = fcn(u)
%#codegen
coder.extrinsic('load');
coder.extrinsic('detect');
persistent detector
if(isempty(detector))
cnnn = load('C:\Users\OBAS\Pictures\Building_Insect_Set\trained\matlab_detector_vgg19_mAP0.81%250epochs.mat');
detector = cnnn.detector;
end
kk = zeros(50,1);
[bboxes,scores] = detect(detector,u);
for i=1:size(scores)
kk(i)=scores(i);
end
y = kk;
%% The Errors
Attempt to extract field 'detector' from 'mxArray'.
Function 'MATLAB Function' (#98.256.260), line 10, column 16:
"cnnn"
Launch diagnostic report.
Component:MATLAB Function | Category:Coder error
Persistent variable 'detector' must be assigned before it is used. The only exception is a check using 'isempty(detector)' that can be performed prior to assignment.
Function 'MATLAB Function' (#98.319.327), line 14, column 26:
"detector"
Launch diagnostic report.
Component:MATLAB Function | Category:Coder error
...
Is there anyway around these errors.
HAMMED OBASEKORE
HAMMED OBASEKORE on 6 Mar 2019
Thanks Patel I eventually got it to work. Here is the correct function inside Matlab Function block in simulink
function [count, bbox ,prob] = fcn(I)
%#codegen
% ensure to initialize your trainned FasterRCNN in the workspace
% I is the Image
coder.extrinsic('evalin')
coder.extrinsic('assignin')
kk= zeros(50,1,'double');
prob = zeros(50,1,'double');
bbox = zeros(50,4,'double');
k=0;
assignin('base','u',I)
[bboxes, scores, cat] = evalin('base','detect(detector,u)')
N = size(scores)
k = N(1)
count = k;
for i = 1:50
if(~isempty(k))
if i > k
break;
end
end
kk(i) = scores(i);
bbox(i,:) = bboxes(i,1:4);
end
prob = kk;

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Arkadiy Turevskiy
Arkadiy Turevskiy on 18 Oct 2021
Edited: Arkadiy Turevskiy on 28 Oct 2021
As of R2021b you can use Deep Learning Object Detector block in Computer Vision Toolbox. For mpre information please see Deep Learning in Simulink page in documentation.

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