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Detect Burn Images with unclassified lidar

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01-10-2019 04:39 PM
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BrandonPrice1
Occasional Contributor

This my final try before manually doing this. I have two unclassified lidar imagery layers. One that has burn data and one that does not. Is there a way to detect it in arcmap other than eyeballing?

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CodyBenkelman
Esri Regular Contributor

Brandon

can you be more specific about your data, and possibly show screenshots?  "classification" for imagery and "classification" for lidar mean very different things, so an unclassified image vs. unclassified lidar would be quite different.

Further, lidar is not imagery, unless you mean the intensity values from the LAS files.  Do you have LAS files, or TIFF files, or something else?

And if you mean "find burned grass and trees" that's quite different from "there used to be a building here, now it's burned to the ground".  If this is the same project as your other posts seeking advice on analyzing before/after images, lidar will be MUCH more effective for identifying burned buildings since you will have a dramatic difference in the DSM (digital surface model) that can be derived from the lidar.  Delineating the extents of burned grassland would more likely be successful using imagery, presuming the imagery was captured recently after the fire (although the lidar intensity image may be effective for this - I don't know that I've seen lidar for a burned area).

re: your other posts, it might also be helpful to know how much total area you're examining (acres/square miles, total # of image files, ANY sort of quantification).  If it's the entire western USA, the recommended solution may be different than if it's 10% of Sonoma County CA.

Cody B. 

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CodyBenkelman
Esri Regular Contributor

Brandon

can you be more specific about your data, and possibly show screenshots?  "classification" for imagery and "classification" for lidar mean very different things, so an unclassified image vs. unclassified lidar would be quite different.

Further, lidar is not imagery, unless you mean the intensity values from the LAS files.  Do you have LAS files, or TIFF files, or something else?

And if you mean "find burned grass and trees" that's quite different from "there used to be a building here, now it's burned to the ground".  If this is the same project as your other posts seeking advice on analyzing before/after images, lidar will be MUCH more effective for identifying burned buildings since you will have a dramatic difference in the DSM (digital surface model) that can be derived from the lidar.  Delineating the extents of burned grassland would more likely be successful using imagery, presuming the imagery was captured recently after the fire (although the lidar intensity image may be effective for this - I don't know that I've seen lidar for a burned area).

re: your other posts, it might also be helpful to know how much total area you're examining (acres/square miles, total # of image files, ANY sort of quantification).  If it's the entire western USA, the recommended solution may be different than if it's 10% of Sonoma County CA.

Cody B. 

BrandonPrice1
Occasional Contributor

Hey Cody:

Thanks for the response. This is non lidar I believe.  An ecw and sid file. The sid file was imagery taken right after the fire as I was saying in response to the post below. It is of the Woolsey Fire which in which a few coastal cities in the LA and Ventura Counties were affected. ArcGIS Web Application 

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BrandonPrice1
Occasional Contributor
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PeterBecker
Esri Regular Contributor

Depends what you mean by "two unclassified lidar imagery layers". If these are Digital Surface Models then you can subtract one from the other and assuming the foliage exist on one and not in the other the different will be very apparent and the resulting raster you that threshold, filter (remove noise) and convert to polygon. Similar if the data is multispectral and you can create a vegetation index and subtract the two then you can do similar. If though the multispectral data is taken in winter and summer in a deciduous area, you are going to get incorrect results. 

BrandonPrice1
Occasional Contributor

These are just georeferenced sid and ecw files I think.   

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BrandonPrice1
Occasional Contributor
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DanPatterson_Retired
MVP Emeritus
BrandonPrice1
Occasional Contributor
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