I've trained a model with a custom dataset (Garfield images) with Tensorflow Object Detection API (ssd_mobilenet_v1 model) and referring it in the android sample application available on Tensorflow repository. The application can only detected the images in distances less or equal 20cm approximately.
Do you have any clue about I can improve the model to perform recognitions in longer distances (about 30cm or more) ?
I don't know with this limitation is related with input size I'm using (tested with images with 300x300 and 68x68) or any custom data augmentation is needed to improve that.
SSD models are known to have worse performance on small objects. Have you tried using one of our FasterRCNN models to see if the result is acceptable?
Related
I trained a model using images I gathered from the web. Then, when inferences were made using images newly collected from the web, performance was poor.
I am wondering how I can improve my dataset using misclassified images. Can I add all the misclassified images to the training dataset? And then do I have to collect new images?
[Edit]
I added some of the misclassified images to the training dataset, although the performance evaluation got better.
It might be worth if you could provide more info on how you trained your model, and your network architecture.
However this are some general guidelines:
You can try to diversify your images in your train set by, yes, adding new images. The more different examples you provide to your network, the higher the chance that they will be similar to images you want to obtain prediction from.
Do data augmentation, it is pretty straightforward and usually improves quite a bit the accuracy. You can have a look at this Tensorflow tutorial for Data Augmentation. If you don’t know what data augmentation is, basically is a technique to perform minor changes to your images, that is by rotating the image a bit, resizing etc. This way the model is trained to learn your images even with slight changes, which usually makes it more robust to new images.
You could consider doing Transfer Learning. The main idea here is to leverage a model that has learned on a huge dataset and use it to fine-tune your specific problem. In the tutorial I linked they show the typical workflow of transfer learning, by taking a model pretrained on the ImageNet dataset (the huge dataset), and retraining it on the Kaggle "cats vs dogs" classification dataset (a smaller dataset, like the one you could have).
I want to build a simple image detector for custom Binary shapes on images.
I may train and use the models on object detection zoo such as ssd_inception_v2 and so on. But it's would be extremely un efficient as it has sizes in hundreds of Megabytes.
and I can't even imagine to use that in my simple app. can anybody suggest me how to solve this?
I have already built excellent small size classifiers for my images. but can't build small scale efficient detector. (their position with detection boxes)
I think what you need is transfer learning. I would take one of the lightweight models such as MobileNetV2 and retrain on my dataset. It should be pretty quick.If you want to even decrease your model size further, feel free to only take the first few layers of the CNN and retrain it. It would be a bit more work since you need to re-write the part of network you want to use and load it with the pre-trained weights.
I am re-training the SSD MobileNet with 900 images from the Berkeley Deep Drive dataset, and eval towards 100 images from that dataset.
The problem is that after about 24 hours of training, the totalloss seems unable to go below 2.0:
And the corresponding mAP score is quite unstable:
In fact, I have actually tried to train for about 48 hours, and the TotoalLoss just cannot go below 2.0, something ranging from 2.5~3.0. And during that time, mAP is even lower..
So here is my question, given my situation (I really don't need any "high-precision" model, as you can see, I pick 900 images for training and would like to simply do a PoC model training/predication and that's it), when should I stop the training and obtain a reasonably performed model?
indeed for detection you need to finetune the network, since you are using SSD, there are already some sources out there:
https://gluon-cv.mxnet.io/build/examples_detection/finetune_detection.html (This one specifically for an SSD Model, uses mxnet but you can use the same with TF)
You can watch a very nice finetuning intro here
This repo has a nice fine tuning option enabled as long as you write your dataloader, check it out here
In general your error can be attributed to many factors, the learning rate you are using, the characteristics of the images themselves (are they normalized?) If the ssd network you are using was trained with normalized data and you don't normalize to retrain then you'll get stuck while learning. Also what learning rate are they using?
From the model zoo I can see that for SSD there are models trained on COCO
And models trained on Open Images:
If for example you are using ssd_inception_v2_coco, there is a truncated_normal_initializer in the input layers, so take that into consideration, also make sure the input sizes are the same that the ones you provide to the model.
You can get very good detections even with little data if you also include many augmentations and take into account the rest of the things I mentioned, more details on your code would help to see where the problem lies.
So I have trained an object detection model with tensorflow.
I retrained the model (ssd_mobilenet_v2) using a data set containing traffic sign with an image size of 1920x1080 each. The trained model worked really well when ran on desktop.
Now when I ran it on mobile using tfMobile, the Model performed poorly. One thing that stood out to me is that the input for the mobile prediction is reduced to 300x300.
How big of an impact is this? Would retraining the model on images with the same size or aspect ratio improve the model accuracy on mobile?
I also feel like my model is way slower than the one provided from the android demo.
I'm training a model to detect meteors within a picture of the night sky and I have a fairly small dataset with about 85 images and each image is annotated with a bounding box. I'm using the transfer learning technique starting with the ssd_mobilenet_v1_coco_11_06_2017 checkpoint and Tensorflow 1.4. I'm resizing images to 600x600pixels during training. I'm using data augmentation in the pipeline configuration to randomly flip the images horizontally, vertically and rotate 90 deg. After 5000 steps, the model converges to a loss of about 0.3 and will detect meteors but it seems to matter where in the image the meteor is located. Do I have to train the model by giving examples of every possible location? I've attached a sample of a detection run where I tiled a meteor over the entire image and received various levels of detection (filtered to 50%). How can I improve this?detected meteors in image example
It could very well be your data and I think you are making a prudent move by improving the heterogeneity of your dataset, BUT it could also be your choice of model.
It is worth noting that ssd_mobilenet_v1_coco has the lowest COCO mAP relative to the other models in the TensorFlow Object Detection API model zoo. You aren't trying to detect a COCO object, but the mAP numbers are a reasonable aproximation for generic model accuracy.
At the highest possible level, the choice of model is largely a tradeoff between speed/accuracy. The model you chose, ssd_mobilenet_v1_coco, favors speed over accuracy. Consequently, I would reccomend you try one of the Faster RCNN models (e.g., faster_rcnn_inception_v2_coco) before you spend a signifigant amount of time preprocessing images.