Raster to Polygon Super slow then not working

[DXXX]

I have a bunch of rasters that I want to convert into polygons, but when I use the tool it is so slow. 3 hours working on 1 .tif gets too 1%. Anyone have any ideas how I can convert my raster data set into polygons?

[SamCoggins1]

How big are the rasters?

You should probably try to run the Raster to polygon tool on a small subset to determine whether it's your tool or the size of the rasters. If the tool is still slow on the subset, then it's a problem with the tool. If it process the rasters perfectly you can probably set up a Python script that uses splits the raster up, converts to polygon, and then merges the polygonised raster back together.

Let me know if you need a hand with the scripting...

[JeffreySwain]

Depending on the original raster there are a few things that can be done.  I would recommend considering why you are converting it as it may not be necessary.  Some of the spatial analyst tools can be used in place of the polygon version of the file with zonal statistics.  If you really want to convert the raster still, then I would recommend using some of the generalization tools to clean up the edges and reduce the number of polygons. You may also consider the multivariate classification to further reduce the variability and create relatively homogenous zones prior to conversion.  Also consider the output format, feature classes are a must as they are not required to be under ~2 Gigs as shapefiles. The output from these conversions is usually rather large.

[SteveLynch]

They key to this discussion is the version of ArcGIS.

Prior to ArcGIS 10 all the rasters are processed as grids and then converted to your raster format and all feature classes are written to shapefile and then finally converted to your format. So if you are using pre 10, your .tif will be converted to grid prior to RasterToPolygon doing it's thing.

In ArcGIS 10 we process the data in it's native format.

-Steve

[DXXX]

Thanks for the response. I am using 10.1. I need to do this process as we need to make payment to a client that has delivered us the aerial imagery so we need to work out how much has been delivered and how much extra we need to cover our work area.

I have tried running the convert Raster to Polygon tool on just 1 aerial photo, not the full set and it still doesn't work.

In the end I need 1 polygon with the area covered by the aerial photos.

[JeffreySwain]

Ok so you are not looking for a classified polygon, you are looking for the outer extent.  I would recommend creating a mosaic dataset and then you will have one polygon per raster. With that description, you should be able to see the amount of work completed.  The polygons created are called footprints and should represent all the rasters delivered. You could look at the count of the rasters(footprints) but be sure you do not create overviews and accidentally count them.

[DXXX]

I have the Raster dataset already in a Mosaic. How ever the footprints do not match up to the actual imagery. See picture. in the end I need to have a polygon the same size of the imagery (picture) and not a polygon the same size as the footprints.

Any ideas? If I have to digitize it will take me days.

[GeospatialTechnology]

What resolution is your raster dataset? If it is high resolution it will take a long time to process. Can you cope with a reduced resolution raster? How about using Resample and altering the cell sizes.

[DXXX]

What resolution is your raster dataset? If it is high resolution it will take a long time to process. Can you cope with a reduced resolution raster? How about using Resample and altering the cell sizes.

Thanks for your response. Can you tell me what options to check to reduce the size? See attached picture.

[JeffreySwain]

All you need to do is build the footprints.  Simply use the ID tool to see the pixel values of the white space in your mosaic dataset and then adjust the settings in the build footprints tool.  By default they are set to eliminate the 0 and 255 pixels. If your rasters have additional values then adjust the min or max values.

You should not have to resample the rasters for this workflow.