How to change the extent values of a raster image in Arcmap 10.1

2944
6
Jump to solution
11-13-2014 04:39 AM
MikeTotti
New Contributor

Hi guys,

I have two raster images that cover the same area but their extents are different because one of the two does not have a projection. How can I copy the extents of the projected raster to unprojected raster so that both images can be overlaid each other? I imported the projection but cannot import the extends. Is there a tool in Arcgis that I can use to do that?

Tags (1)
0 Kudos
1 Solution

Accepted Solutions
ChrisDonohue__GISP
MVP Frequent Contributor

If the two images were in the same projection originally, and covered exactly the same extents, it may be possible to line them up by copying the World File from the working one and then renaming the copy to the file name of the non-working one.  For example, for a tif image, copy goodtif.tfw and rename it to the other rasters name (and keep the .tfw extension). Then open a brand new ArcMap session and load them both in.  Note that you definitely need to start a new session - the addition of a world file won't help for images already loaded into ArcGIS.

However, the liklihood that the images are exactly the same is a longshot.  More likely Georeferencing will need to be employed to get the two aligned.

One thing that would be helpful to know in terms of troubleshooting this is the raster file type of the imagery you have.  Are they tiffs, sids, jpg, or another of the many image formats?  This information is helpful to know as different rasters have different properties.  For example, some rasters also can have the extent embedded in the raster itself, which can override the world file.

Chris Donohue, GISP

View solution in original post

6 Replies
JakeSkinner
Esri Esteemed Contributor

Hi Mike,

You will want to georeference the raster.  Take a look at the following link for the steps on how to do this:

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

MikeTotti
New Contributor

Thanks Jake but the images still do not overlay perfectly each other after georeferencing.

0 Kudos
MelitaKennedy
Esri Notable Contributor

As Jake said, you may have to georeference the raster that doesn't have a coordinate system definition.

However, is it georeferenced (has real world coordinates) already or does it have raw image values (extent is the number of cells like 0 to 1000)?

If it does have real world coordinates, but you just don't know what the coordinate system is, you could try posting the raster's extents plus the area it represents (county, city, lat/lon, etc.) and perhaps someone could offer some suggestions.

Melita

MikeTotti
New Contributor

Hi Melita,

The unprojected image is in gif format. I have attached the extent values of this gif image. Untitled.jpg

0 Kudos
ChrisDonohue__GISP
MVP Frequent Contributor

If the two images were in the same projection originally, and covered exactly the same extents, it may be possible to line them up by copying the World File from the working one and then renaming the copy to the file name of the non-working one.  For example, for a tif image, copy goodtif.tfw and rename it to the other rasters name (and keep the .tfw extension). Then open a brand new ArcMap session and load them both in.  Note that you definitely need to start a new session - the addition of a world file won't help for images already loaded into ArcGIS.

However, the liklihood that the images are exactly the same is a longshot.  More likely Georeferencing will need to be employed to get the two aligned.

One thing that would be helpful to know in terms of troubleshooting this is the raster file type of the imagery you have.  Are they tiffs, sids, jpg, or another of the many image formats?  This information is helpful to know as different rasters have different properties.  For example, some rasters also can have the extent embedded in the raster itself, which can override the world file.

Chris Donohue, GISP

MikeTotti
New Contributor

Thanks Chris for the tip. I could give the exact extent values of the projected image to unprojected gif image manually in Erdas Imagine but just could not find a way to do it in Arcmap. Thanks for your help though.

0 Kudos