SMRF - often have "a small number of cells"

WebODM
#1

Using the default -
smrf-window

Simple Morphological Filter window radius parameter (meters). Default: 18.0

often gives me this warning towards the end of processing when working on datasets of a few hundred images or less (I’m not sure where the image number cut-off is for not having a small number of cells).

(pdal translate filters.smrf Warning) SMRF running with a small number of cells (2208). Consider changing cell size.

2208 doesn’t sound like a small number, so what is considered to be a reasonable number of cells, and should I be operating with a smaller parameter than 18m for small areas?

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#2

Cells, if PDAL is operating like other GIS software, are GSD-dependent. So if your GSD is 0.1cm/px, 2208 cells (in either X/Y) is really not all that much on the ground.

What is your GSD?

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#3

0.5cm in that case, with 177 M2P full sized (5472) CPU feature extracted images.

Same dataset resized to 2/3 (3644) to process with GPU was 0.7cm and didn’t show that warning.

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#4

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