[gdal-dev] Recommended process for running a intersect test between a raster and a simple vector

Patrick Young patrick.mckendree.young at gmail.com
Tue Jan 14 19:09:05 PST 2020

One trick I like regarding accessing overview levels is to use the open
option to snag a handle direct to the overview level (see Even's post
then you can run polygonize against a much smaller dataset.  If it's a COG
presumably it has internal overviews.

On Mon, Jan 13, 2020 at 12:22 PM Brian <mulcahy.brianp at gmail.com> wrote:

> So I am not sure if this is the right place or not. Feel free to remove if
> it is not.
> The problem:  I am needing to see if an extent (vector polygon, 4
> vertices) has any interaction with a raster stored in the cog format.
> I thought about using raster_polygonize and running a intersect but that
> is going to be way too slow and I don't need the detail at which the raster
> is stored in.
> So I was thinking of some alternatives.
> Is there anyway to output just the polygon of the raster at a certain
> overview level?
> Is there any way to run intersects on a raster without converting it?
> I know I can retrieve the extent of the raster and quickly determine if an
> extent has any interaction with that raster extent. I also know that I can
> send points(x,y) and retrieve the value of the raster at that point is
> there any way to manipulate /game this? Maybe sending the extent as
> individual points with added points in between the vertices and just
> running multiple value at location operations? For my need, some false
> positives would be acceptable. If it helps raster data is of rivers and
> inundations.
> Has anyone else come up with some type of process for this?
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