Usaphotomaps Jpg To Ge

[planewood]

I have a large jpg file created by USAPhotomaps that covers about 2 miles x 2 miles at 1 meter resolution. All the lat/longs or UTM's check out perfect with USAPhotomaps. They are as close as I can read off my maps and surveyed locations.

 

When I use Google Earth to overlay this jpg file I'm getting some distortion. The bottom of the JPG files is lined up great in the N/S & E/S directions. The south section line lines up exactly as do the SW & SE section corners (the GE lat/lons read what they should read at the known points). But, the top of the jpg is skewed right by about 70'. The skewing gets progressively worse from bottom to top. Another way to look at it is that the waypoints at the top are plotting about 70' west of where they should relative to the overlayed jpg file.

 

Nothing is said in GE about the type of projection or datum their using. I wonder if that is the cause?

 

Anyone encountered this before?

[Neo_Geo]

Perhaps you have the GE globe tilted in some direction or another whereas you need to zoom directly straight down to the center of the image area.

[+Timpat]

I work in the GIS field, and have used USAPhotoMaps a lot to grab aerial photos if none others are available. The answer lies in the fact the USAPhotoMap image data is "projected" in UTM, where GE works in a geographic coordinate system (GCS), Lat/Lon, which is WGS 84.

[planewood]

I work in the GIS field, and have used USAPhotoMaps a lot to grab aerial photos if none others are available. The answer lies in the fact the USAPhotoMap image data is "projected" in UTM, where GE works in a geographic coordinate system (GCS), Lat/Lon, which is WGS 84.

 

Wonder if there is anyway out there to 're-project' an image file??

 

I got to wondering the same thing when I saw the section line points not lining up with the lat/lon grid. In this part of the country, the UTM grid is about 1 degree out of tilt with the lat/lon. 1 degree in a mile is about 90'. The section lines don't line up either, but are close.

 

And thank you for explaining this.

[+Timpat]

Wonder if there is anyway out there to 're-project' an image file??

There is, but it requires some pretty expensive software. We have all this in our GIS toolbox, but I couldn't afford it for playing at home. Check out Lizardtech GeoExpress to see what this is all about. I'm sure there are other programs. Cool stuff that we get to play with at work!

[planewood]

Wonder if there is anyway out there to 're-project' an image file??

There is, but it requires some pretty expensive software. We have all this in our GIS toolbox, but I couldn't afford it for playing at home. Check out Lizardtech GeoExpress to see what this is all about. I'm sure there are other programs. Cool stuff that we get to play with at work!

 

Tim -

 

Oklahoma State Univ has all the counties for OK in MrSid format, taken 2003. Only problem is the photos were taken in the summer.

 

But, a crop from one of the MrSid counties lines up almost perfectly. That's telling me that their photos are using a geodetic projection. I thought it might cause of the MrSid, LizardTech, Google connections.

 

BTW - I think it might have been LizardTech that bought out portions of the old TMS, Sequoyah, that was headquarted in Stillwater, OK (home of OSU). I lost a few K$ when that company went under!

 

I graduated from OSU in 1965.

Edited March 24, 2006 by planewood

[+Kelt.]

Greetings,

I've been watching this thread as it pertains to my new line of work as a researcher at a survey company. The whole business is new to me, but thankfully I have some very patient and talented teachers and supervisors.

In your experience, are there any "must -have" applications for this field..I already use autocad LDD, and have a picture viewer that will handle .jp2 images (for DOQQ's). I'm in Florida, and am blessed with a site called LABINS ( www.labins.com) that collects lots of information in one place.. CCRs, GLO etc..., I'm beginning to learn how to collect data and change it into a format that can be uploaded to my handheld gpsr , but that's personal, albeit tied closely to the professional side of my life.

 

So much to learn, and thankfully resources like this place to help me along.

[planewood]

Greetings,

I've been watching this thread as it pertains to my new line of work as a researcher at a survey company. The whole business is new to me, but thankfully I have some very patient and talented teachers and supervisors.

In your experience, are there any "must -have" applications for this field..I already use autocad LDD, and have a picture viewer that will handle .jp2 images (for DOQQ's). I'm in Florida, and am blessed with a site called LABINS ( www.labins.com) that collects lots of information in one place.. CCRs, GLO etc..., I'm beginning to learn how to collect data and change it into a format that can be uploaded to my handheld gpsr , but that's personal, albeit tied closely to the professional side of my life.

 

So much to learn, and thankfully resources like this place to help me along.

 

USAPhotoMaps is a good (shareware) one to use. It pulls aerial photo's down from Terrraserver with down to 1 meter resolution. It will let you create tracks and waypoints that can be uploaded to your GPS. GPSBabel will let you convert from the dozens of GPS related formats to another format.

 

See the thread on "What software do you use?"

[GeoidPS]

As I was trying to explain to some yokels, UTM does not have the accuracy of WGS, or NAD because it is like trying to flatten a cap to a flat surface. This is why there is an adjustment in the zoning as moving up/down/sideways to get the "best fit".

Anybody try to flatten the cut off top of a basketball? Any questions?

[planewood]

As I was trying to explain to some yokels, UTM does not have the accuracy of WGS, or NAD because it is like trying to flatten a cap to a flat surface. This is why there is an adjustment in the zoning as moving up/down/sideways to get the "best fit".

Anybody try to flatten the cut off top of a basketball? Any questions?

 

The Universal Transverse Mercator representation is just one of many ways for projecting locations on a spherical surface to a flat surface. Converting UTM coordinates back to lat/lon coordinates is quite accurate as long as you limit the calculations to points that are in each defined UTM zone. If, for instance, you say the points are in zone 15R but they are actually in zone 20T, then yes, the resulting calculations will give inaccurate lat/lon's.

[+blindleader]

USAPhotoMaps is a good (shareware) one to use. It pulls aerial photo's down from Terrraserver with down to 1 meter resolution.

.25 m/pixel in color in quite a few urban areas. You definitely want a high speed connection and a gigantic disk drive.

[ardfarkle]

 

Wonder if there is anyway out there to 're-project' an image file??

 

I believe GE has tools for re-projecting an image manually to 'flatten' (for lack of a better word) and skew as needed. I've seen a section in the help file on this but I don't have GE on this computer (server), so I can't check right now.