topic Re: Converting images from WGS-84 to UTM in several zones in Coordinate Reference Systems Questions

Converting images from WGS-84 to UTM in several zones

JanaZieglerova1 — Fri, 27 May 2016 08:45:25 GMT

Hello,

I have a several .tiff with .tfw file in WGS-84 and I want to split these images according to UTM zones and of course convert these images to UTM too. Is there any simple way how to do it? Thanks.

Re: Converting images from WGS-84 to UTM in several zones

DanPatterson_Retired — Fri, 27 May 2016 08:56:03 GMT

Pick your UTM zones https://www.arcgis.com/home/item.html?id=715d4d6a36cc4b019bd84cb34ce37647

Clip the rasters

Project each raster according to the appropriate UTM zone

Since this is probably a one-off, no need for fancy scripting although batch clip and batch project would be possible

Re: Converting images from WGS-84 to UTM in several zones

NeilAyres — Fri, 27 May 2016 09:22:21 GMT

Just a picky point about terminology...

Its not IN WGS-84, because WGS84, by itself, is not a coordinate system. It can be GCS_WGS84, ie geographic coordinates (decimal lat/long) based on WGS84.

But finding the zone is fairly easy if you know what the longitude (of maybe the centre) of the image.

If you are west (ie negative) of Greenwich, Zone # = int(abs(long) / 6) + 1; if east (like me),

Zone # = int((long + 180) / 6) + 1

Re: Converting images from WGS-84 to UTM in several zones

JanaZieglerova1 — Fri, 27 May 2016 11:35:20 GMT

Of course I mean GCS_WGS84....

I don't need to find UTM zone, but the way how to split image and convert it to relevant UTM zone. Isn't there other form than clip raster into UTM zones and each new raster convert to relevant UTM zone?

Re: Converting images from WGS-84 to UTM in several zones

NeilAyres — Fri, 27 May 2016 12:35:20 GMT

If you want to convert each GCS image into another one which is in UTM coordinates, you will have to project that image.

ArcGIS Desktop

General workflow would be find the zone number, find the WKID or identifier for that UTM system and zone.

Re project the image.

Re: Converting images from WGS-84 to UTM in several zones

DanPatterson_Retired — Fri, 27 May 2016 12:47:14 GMT

If you want to manually enter the extent of the utm zone in decimal degrees then you can export that extent.

Remember a UTM zone in decimal degrees, is a lune ... 6 degrees wide then there are all these fiddly rules about dividing the lines of latitude into 8ish degree chunks except at the poles and some chunk somewhere else ...

Or, just grab the utm zone from the file I posted

Clip, project, ship

Re: Converting images from WGS-84 to UTM in several zones

JanaZieglerova1 — Fri, 27 May 2016 13:17:30 GMT

But I have a problem, that each GCS image overlays 2 or 3 UTM zones....

Re: Converting images from WGS-84 to UTM in several zones

DanPatterson_Retired — Fri, 27 May 2016 13:22:27 GMT

That is too wide to fit into one utm zone, you will have to use another projection with a larger east west extent. The choice depends where you are, but a Lambert conformal conic is appropriate for some regions.

If you want to stick with UTM, then you should stick with the 6 degree width (or perhaps a bit more if you want overlaps, but the more you extend, the worse it gets)