OpenCV random forest: Setting a random seed - opencv

Since there is randomness involved in the computation of a random forest classifier, it is necessary to define a random seed to get reproducible results. How does one do this for OpenCV CvRTrees? I do not see such a parameter in CvRTParams.
Update: The API change of OpenCV 3 removed CvRTParams. However, the title question remains.

it depends on the opencv version you are using.
While 2.4.9 seems to use the global cv::theRNG() , where you can just set theRNG().state = something,
This no longer seems to be possible in opencv3.0

Related

Use .tflite with iOS and GPU

I have created a new tflite model based on MobilenetV2. It works well without quantization using CPU on iOS. I should say that TensorFlow team did a great job, many thanks.
Unfortunately there is a problem with latency. I use iPhone5s to test my model, so I have the following results for CPU:
500ms for MobilenetV2 with 224*224 input image.
250-300ms for MobilenetV2 with 160*160 input image.
I used the following pod 'TensorFlowLite', '~> 1.13.1'
It's not enough, so I have read TF documentation related to optimization (post trainig quantization). I suppose I need to use Float16 or UInt8 quantization and GPU Delegate (see https://www.tensorflow.org/lite/performance/post_training_quantization).
I used Tensorflow v2.1.0 to train and quantize my models.
Float16 quantization of weights (I used MobilenetV2 model after Float16 quantization)
https://github.com/tensorflow/examples/tree/master/lite/examples/image_segmentation/ios
pod 'TensorFlowLiteSwift', '0.0.1-nightly'
No errors, but model doesn’t work
pod 'TensorFlowLiteSwift', '2.1.0'
2020-05-01 21:36:13.578369+0300 TFL Segmentation[6367:330410] Initialized TensorFlow Lite runtime.
2020-05-01 21:36:20.877393+0300 TFL Segmentation[6367:330397] Execution of the command buffer was aborted due to an error during execution. Caused GPU Hang Error (IOAF code 3)
Full integer quantization of weights and activations
pod ‘TensorFlowLiteGpuExperimental’
Code sample: https://github.com/makeml-app/MakeML-Nails/tree/master/Segmentation%20Nails
I used a MobilenetV2 model after uint8 quantization.
GpuDelegateOptions options;
options.allow_precision_loss = true;
options.wait_type = GpuDelegateOptions::WaitType::kActive;
//delegate = NewGpuDelegate(nullptr);
delegate = NewGpuDelegate(&options);
if (interpreter->ModifyGraphWithDelegate(delegate) != kTfLiteOk)
Segmentation Live[6411:331887] [DYMTLInitPlatform] platform initialization successful
Loaded model 1resolved reporterDidn't find op for builtin opcode 'PAD' version '2'
Is it possible to use MObilenetV2 quantized model on IOS somehow? Hopefully I did some mistake :) and it's possible.
Best regards,
Dmitriy
This is a link to GITHUB issue with answers: https://github.com/tensorflow/tensorflow/issues/39101
sorry for outdated documentation - the GPU delegate should be included in the TensorFlowLiteSwift 2.1.0. However, looks like you're using C API, so depending on TensorFlowLiteC would be sufficient.
MobileNetV2 do work with TFLite runtime in iOS, and if I recall correctly it doesn't have PAD op. Can you attach your model file? With the information provided it's a bit hard to see what's causing the error. As a sanity check, you can get quant/non-quant version of MobileNetV2 from here: https://www.tensorflow.org/lite/guide/hosted_models
For int8 quantized model - afaik GPU delegate only works for FP32 and (possibly) FP16 inputs.

How the initial kmeans points works in to BigQuery ML?

I'm using BigQuery for machine learning, more specifically the k-means method for an unlabeled dataset where I'm trying to find clusters.
I'd like to know if someone has discovered how the BQ ML initiates the centroids.
I already tried looking at the documentation but either there is nothing or I couldn't find it.
CREATE MODEL `project.dataset.model_name`
OPTIONS(
model_type = "kmeans",
num_clusters = 3,
distance_type = "euclidean",
early_stop = TRUE,
max_iterations = 20,
standardize_features = TRUE)
AS
(SELECT * FROM `project.dataset.sample_date_to_train`
)
The results differ a little each time I run.
Has someone experience with that subject?
For someone who is still looking for an answer, recently there has been an update on BigQuery ML about this topic. Two new paramaters have been added to the CREATE MODEL statement, i.e.:
KMEANS_INIT_METHOD
KMEANS_INIT_COL
Basically you can set your custom K observations (belonging to the data table) that will serve as initial centroids for your K-means algorithm. You can find the relative documentation at this link. Maybe it's not the most exciting solution to your problem, but it's still something you can work with if you need reproducibility.
If I had to guess, it probably uses a similar logic to TensorFlow (BQML might be using TF under the hood as it is). Random partitioning seems to be the TensorFlow default, so that would be my guess.
The reason you are seeing different results each time you train the model, is due to the random nature of the initial values assigned to the centroids. The K-means algorithm begins by randomly selecting a value(position) for the k number of centroids chosen. If you review this documentation it explains the exact process when using the K-means algorithm1.

Find out the training error after fit()

I'm training a LinearSVC model and I want to get the training error of it. Is it possible to get it w/o evaluating it manually?
Thanks
sklearn is using liblinear for this task.
You can take a quick glance into the sources here:
self.coef_, self.intercept_, self.n_iter_ = _fit_liblinear(
X, y, self.C, self.fit_intercept, self.intercept_scaling,
self.class_weight, self.penalty, self.dual, self.verbose,
self.max_iter, self.tol, self.random_state, self.multi_class,
self.loss, sample_weight=sample_weight)
which shows that only coefficients, intercepts and number of iterations are processed by sklearn's python-API. Whatever else is available in liblinear's output is not grabbed. You can't directly read out the training-error without changing the internal code.
There might be a possible hack turning on verbose-mode, redirect the output and parse additional info available there. But this assumes the info you look for is available there and it's also hacky and i won't recommend it.
Just use the score-method. It won't be too costly compared to fitting.

OpenCV - training new LatentSVMDetector Models

I haven't found any method to train new latent svm detector models using openCV. I'm currently using the existing models given in the xml files, but I would like to train my own.
Is there any method for doing so?
Thank you,
Gil.
As of now only DPM-detection is implemented in OpenCV, not training.
If you want to train your own models, the most reliable approach is to use Felzenszwalb's and Girshick's matlab code (most of the heavy stuff is implemented in C) (http://www.cs.berkeley.edu/~rbg/latent/)(http://www.rossgirshick.info/latent/) It is reliable and works reasonably fast
If you want to do it in C-only, there is an implementation here (http://libccv.org/doc/doc-dpm/) that I haven't tried myself.
I think there is a function in the octave version of the author's code here
(Octave Version of DPM). It is in step #5,
mat2opencvxml('./INRIA/inriaperson_final.mat', 'inriaperson_cascade_cv.xml');
I will try it and let you know about the result.
EDIT
I tried to convert the .mat file from the octave version i mentioned before to .xml file, and compared the result with the built in opencv .xml model and the construction of the 2 xmls was different (tags, #components,..), it seems that this version of octave dpm generates xml files for later opencv version (i am using 2.4).
VOC-release3.1 is the one matches opencv2.4.14. I tried to convert the already trained model from this version using mat2xml function available in opencv and the result xml file is successfully loaded and working with opencv. Here are some helpful links:
mat2xml code
VOC-release-3.1
How To Train DPM on a New Object

How to compute SVD using Cimg (or maybe openCV or eigen library)?

May anyone give me a quick guide on how to use Cimg to compute SVD for a 3-dimension array?
I just want to get the decomposition of the array in order to compress it small for speeding up further process.
What value should I input at where, and how to get the output?
I've been searched around and still can't understand how it works. and not really fully understand how SVD works as well..only know that it can used to decompress matrix.
At the same time I found that OpenCV and Eigen library also can done the job, do let me know their steps if is much more easier..
(Alternative for me instead of SVD is PCA, which I found its source/library but also don't know how to use..)
Thanks!
See http://cimg.sourceforge.net/reference/structcimg__library_1_1CImg.html#a9a79f3a0849388b3ec13bd140b67a12e
CImg<float> A(3,3); // A = U'*S*V
A.rand(0,1);
CImgList<float> USV = A.get_SVD(); //USV[0] = U and so forth

Resources