Image Rectification

Nakela

Hi there,

I am rectifying a Google Earth image in Global Mapper v18. I add in my Ground Control Points and then my image, and proceed to matching up the points. When I save the rectified image as a GeoTiff however and open it in ArcMap v10.4.1, the following notification pops up:

"One or more of the added layers has an extent that is not consistent with the associated spatial reference information. 

Re-projecting the data in such a layer may lead to unexpected behavior. Use ArcCatalog to confirm the spatial reference is correct and adjust if necessary."

When I open up the layer properties of the GeoTiff in Arcmap, it seems as though the extent of the raster has changed during the export. The extent of the top, bottom, left and right are in the thousands, instead of between -180 to 180 (longitude) and -90 to 90 (latitude).

How I can correct this? Please help.

Thanks. 

BillB

Hi Nakela

I can't really help with you question about rectified imagery, but I was wondering why you were rectifying GE imagery in the first place?  Can't you just load Google Maps Imagery via File > Download online maps imagery?

Nakela

HI Bill,
Thanks for your response.
My company requires us to rectify a GE image of our study area for use in ArcMap, where we use the image as the base map. 

If there is a way to download up to date GE imagery though on Global Mapper and export this to ArcMap, that would be great. 

BillB

Take a look at:

File > Download online imagery > Google Maps Imagery. 

Select a reasonable boundary (eg current screen or a polygon which has previously been selected.  Google Maps imagery is usually (but not always) the same imagery as used in Google Earth. Once downloaded, you should then be able to export to GeoTiff.

This

https://www.globalmapperforum.com/discussion/comment/49906/#Comment_49906

and this

https://www.globalmapperforum.com/discussion/comment/50502/#Comment_50502

may help, in terms of keeping your data downloads and exports to a reasonable size.

Nakela

Thanks for the detail.
Unfortunately I have no option on my Global Mapper to download Google Maps imagery.
But no worries, I will continue to use image rectification. 

Thanks for the help!! 

Amanda McDermott

Hi Nakela,

You certainly should be able to download google earth imagery within the program. I remember we had a similar issue with a new version of globalmapper once, where the online imagery we were used to using seemed to have disappeared - we had to re-link to it.

I think you will find the answers in this thread: https://www.globalmapperforum.com/discussion/9768/bing-maps-aerial-photo-data - particularly the .xml file posted by the administrator J|an 2014. If you save the file, and then 'add sources from file' in the 'download online imagery' dialogue box, I think that might be the answer. Hope that helps!

sphillips

Maybe you need to re-check that your ground control points are using the same projection as you specified in the Image Rectifier window (via Select Projection ... - see below). For example, the default projection is Geographic (Lat/Long) and that requires Long/Lat inputs as opposed to X/Y values in thousands.

As Nakela mentioned you can download the xml file from the link above and add Google Earth and Bing to your download sources if you don't already have it.

If you are also using ArcMap you might want to look into 'Portable Basemap Server'. Basically it's a way to add multiple online sources including Google Earth to your basemaps.