Hi,

Please find my answers enclosed. Bottom line is that we have some components but we are still missing other ones to perform a complete OBIA scheme. This thread could be an opportunity to start a discussion on what is missing. We could then write a Request For Comments about that.

Regards,

Julien

Le 24/01/2017 à 15:46, Sébastien G. a écrit :
Hi,

Since recent OTB versions there is a very nice new framework for classifictaion (PolygonStatistics, SampleSelection, SampleExtraction,TrainVectorClassifier) that allow to train model on vector data.

Can anyone tell me an OTB recipee to use these new tools for object-based classification, including the following steps : 1- Derive features from a raster images on a segmentation (mean, standard deviation of radiometric channels, or shape features)
There is this step from the Large Scale MeanShift segmentation workflow :

https://www.orfeo-toolbox.org/CookBook/recipes/improc.html#step-4-vectorization

Will work with any pair of segmentation/input image as long as they share the same sampling grid (i.e. same size/orgin/spacing).

There are also similar things in this remote module :

https://github.com/sertit/SertitObject

2- Train a vectorClassifier knowing a class attributes on a sample of the (segmentation with features).
This is covered by TrainVectorClassifier application, which can learn from points but also from polylines or polygons. The problem is to get the labels to train the polygons. Aside from manual editing, we are missing some tools to perform automatic labelling of polygons from a reference layer.

3- Apply the model on the vector data (segmentation with features)

This is covered by OGRLayerClassifier application;


Best regards,
Sébastien
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CNES - DSO/SI/2A

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