Convolution and kernel filters for rasterdata

Hello,

I am wondering if its possible to implement Imageprocessing tools in FME?

For instance: Lets say you have a LIDAR file and want to make presentable contours. You then take ur filltered LIDAR file, do some processing to it first, then you make contours, write the contourvector to a raster, and on the raster I would like to have to oportunity to do Image processing, with a convolution/kernel filter.

Can this be implemented i FME?

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Hi,

The ContourGenerator or the SurfaceModeller transformer can be used to generate contour from point cloud. And then, you can use the VectorOnRasterOverlayer to draw the contour onto a raster.

Try them.

Takashi

Hi,

You will have to introduce the image processing filter yourself, since no transformer exists for the job.

See the following page for some examples.

Itay

I am afraid that on the subject of convolution and other kernel techniques the answer is a no. At least, I tried this about 2 years ago and couldn't get it to work. Don't think it has changed since.

There's a possibility for small kernels: duplicating the raster onto different bands (say 8 times) and moving them all by 1 cell will allow you to make a fake 3x3 kernel, using a rasterexpressionevaluator and using different bands instead of different neighbours for the calculations. This gets cumbersome (and slow) fast.

I tried accessing the raster data from the python API to use it with a custom kernel processor, but I've not found a way to do this. Preferably you'd access the data as a 2D array, the rest is reasonably easy. If you do find a way, please let me know!

Thanks for the reply. I will probably need a 7x7 kernel to smoothen the lines and its only one band, so I cant use this technik.

Guess I have to output the raster then to the kernel filtering.

Hi, @paal, @kim, check this out! I tried to create a RasterConvoluter as an image processing tool on FME Hub. It only supports a single real*64 band type, however for starters sake... Anyway, FME has plenty of tools to translate any kind of raster to real*64 and back to colored images. Have fun with it.

Hi @paal @kim

I'm happy to report that we implemented support for raster lens processing in FME 2018.1 and 2019.0 with the new RasterConvolver transformer.

For more info see these articles:

https://blog.safe.com/2018/07/fme-and-convolution-evangelist176/

https://knowledge.safe.com/articles/74523/neighborhood-functions.html

https://knowledge.safe.com/articles/72616/edge-detection-with-the-rasterconvolver.html

https://knowledge.safe.com/articles/72505/raster-slope-calculations-as-a-rasterconvolver-exa.html

Hi @paal @kim

I'm happy to report that we implemented support for raster lens processing in FME 2018.1 and 2019.0 with the new RasterConvolver transformer.

For more info see these articles:

https://blog.safe.com/2018/07/fme-and-convolution-evangelist176/

https://knowledge.safe.com/articles/74523/neighborhood-functions.html