Question about projection conversion with ERDAS ViewFinder

[JonPatch]

Folks,

Dick kicked me out of "Other" and into here . . . .

Issue 1: I'm attempting to use ERDAS ViewFinder to convert an image from UTM. Problem is the image currently doesn't have any projection name in it (it's WGS84). It reports corner coordinates and pixel size, but look at Output File Options, the Change Output Projection area is grayed out. If I look at the image info, the projection is reported as unknown.

Unfortunately the program "help" doesn't work either.

Ideas?

Issue 2: a second image does allow me to convert to WGS 84. But resample chokes on it: "GeoTIFF: Only geographic coordinates are supported. Unable to open data source ..."

Listgeo reports the following for this image:

Geotiff_Information:
Version: 1
Key_Revision: 1.0
Tagged_Information:
ModelTiepointTag (2,3):
0 0 0
-6.08983333e-005 93.1666667 0
ModelPixelScaleTag (1,3):
0.00666667 0.00666667 0
End_Of_Tags.
Keyed_Information:
GTModelTypeGeoKey (Short,1): ModelTypeProjected
GTRasterTypeGeoKey (Short,1): RasterPixelIsArea
GTCitationGeoKey (Ascii,211): "IMAGINE GeoTIFF Support\nCopyright 1991 - 2001 by ERDAS, Inc. All Rights Reserved\n@(#)$RCSfile: egtf.c $ $Revision: 1.6.1.4 $ $Date: 2001/04/23 14:58:04Z $\nProjection Name = UTM\nUnits = feet\nGeoTIFF Units = feet"
ProjectedCSTypeGeoKey (Short,1): PCS_WGS84_UTM_zone_10N
PCSCitationGeoKey (Ascii,202): "IMAGINE GeoTIFF Support\nCopyright 1991 - 2001 by ERDAS, Inc. All Rights Reserved\n@(#)$RCSfile: egtf.c $ $Revision: 1.6.1.4 $ $Date: 2001/04/23 14:58:04Z $\nUTM Zone 10N\nEllipsoid = WGS 84\nDatum = WGS 84"
ProjLinearUnitsGeoKey (Short,1): Linear_Foot_US_Survey
End_Of_Keys.
End_Of_Geotiff.

PCS = 32610 (name unknown)
Projection = 16010 ()
Projection Method: CT_TransverseMercator
ProjNatOriginLatGeoKey: 0.000000 ( 0d 0' 0.00"N)
ProjNatOriginLongGeoKey: -123.000000 (123d 0' 0.00"W)
ProjScaleAtNatOriginGeoKey: 0.999600
ProjFalseEastingGeoKey: 500000.000000 m
ProjFalseNorthingGeoKey: 0.000000 m
GCS: 4326/WGS 84
Datum: 6326/World Geodetic System 1984
Ellipsoid: 7030/WGS 84 (6378137.00,6356752.31)
Prime Meridian: 8901/Greenwich (0.000000/ 0d 0' 0.00"E)
Projection Linear Units: 9003/(unknown) (1.000000m)

Corner Coordinates:
Upper Left ( -0.000, 93.167)
Lower Left ( -0.000, -0.000)
Upper Right ( 121.800, 93.167)
Lower Right ( 121.800, -0.000)
Center ( 60.900, 46.583)

Jon

 

[rhumbaflappy]

Hi Jon.

When you use Erdas ViewFinder, the menu ( Tools...Image Information ) should give you the info the TIFF contains.

When you save an image, the "Output File Options" tab looks like this:

You need to un-gray the options by ticking the boxes:

Note that you need to change the units to degrees, and change the Catagory to Geographic, and the Projection to Lat/Lon (WGS84).

Then press OK, and it should save it where you indicated on the "File" tab... making sure you use type TIFF.

Dick

 

[JonPatch]

Hi Dick, thx for the clarification. And I still have a grayed-out file options tab in the file I'm trying to resample.

The steps I've taken are:

1. convert from MrSid to GeoTIFF useing mrsiddecode
2. create .tfw using GeoTIFFExamine (copied data to world file) (see attached)
3. embed tags using geotifcp

I've taken the output of both step 2 and step 3 into ERDAS Viewer and in both cases the output file options are not available. (see image)

Curiously, I seem to have converted the MrSID file long ago using some other TIFF converter, the file is a tiny bit larger, and when I ran that through ERDAS Viewer it aborted on an error, "Invalid corners." But I can't recreate that TIFF.

Jon

 

[scott967]

I have to say I have never seen UTM data in units of U.S. Survey Feet. Where did you get the metadata?

But, after going through this way too many times (in my case I had mainly SPCS and UTM data, but also an interest in FS scenery), i broke down and bought Global Mapper. All these problems were immediately solved.

scott s.
.

 

[HolgerSandmann]

Hi Jon,

even if you don't want to spend the money on a GM licence you can use the demo to examine your image and double-check its parameters.

For issue 2 how does the metadata you received compare to the information in the Listgeo report? Feet as units for UTM seems unlikely but also the fact that the corner coordinates are given in degrees, not UTM coordinates.

If this is the output after transformation to geographic then the units should be in degrees not feet.

Cheers, Holger

 

[JonPatch]

Thx for the responses, guys.

Because I'm dealing with a couple of issues at once, I think it best I focus on just one: the situation where I have a MrSID image that I want to convert to a tagged GeoTIFF. As mentioned earlier the challenge is that the conversion option is grayed out in ERDAS Viewer. So to reiterate:

- I used MrSIDDECODE to create a TIFF
- for this resulting TIFF listGeo reports tiepoints, pixelscale, rasterstypegeokey and corner coordinates, in metres UTM referenced
- I used GeoTIFFExamine to confirm that this TIFF is georeferenced, and to create a world file
- I open the result with ERDAS ViewFinder: it confirms the coordinates, and that there is no projection info
- In ERDAS ViewFinder, in the Output File Options, "Change Output Pixel Size" and "Change Output Projection" options are both grayed out and cannot be selected.

I hope that's more clear. The other file in feet is another kettle of fish, which I'll deal with after, and probably in a different way.

I do see that the registered version of Global Mapper would solve my issue, as the evaluation version prompts me for the projection and datum, including the UTM zone. Consider me cheap. And I'd like to understand this process as well.

EDIT: what I know I need to able to tell the program to convert the projection is that it is currently UTM, in metres and Zone 10.

Jon

 

[rhumbaflappy]

Hi Jon.

I suspect the problem lies right at the start. The MrSIDDECODE program may be oddly skewing the process.

Is there any way you could link us to the original source file ( MrSid ? )

Also, the Erdas Viewfinder can load MrSid files... why not just do that?

Dick

 

[JonPatch]

Hi Dick,

Yup, I should have mentioned that I did load the MrSID file directly into ERDAS ViewFinder. Result was the same. Grayed out save-as options.

The image is copyright, and 37Mb (compressed!) or so, but if you were willing to look at it I could provide you a secure FTP link. It's a 750 Mb image when converted to TIFF.

I'll contact you offline.

Jon

 

[José]

If you don't want to invest in GM, there's a limited but free version of that program.

dlgv32 Pro is a limited-feature version of commercial software called Global Mapper which was created from the original dlgv32 source code. Improved to address changes in data standards and to better meet customer requirements, dlgv32 Pro continues the tradition of providing quality viewing software for USGS data users. The USGS has obtained from Global Mapper a license to freely distribute this limited-feature version.

Available at: http://mcmcweb.er.usgs.gov/drc/dlgv32pro/

Regards,

José

 

[JonPatch]

Hi Jose,

Thanks for the response. I do have dlgv32, however the ability to reproject is disabled.

What I learned offline from Dick is that it'll be difficult to do what I want with particular types of files without a program like GM or something similar.

Jon

 

[José]

Forgive my fault. I didn't know the reproject ability was disabled in dlgv.

I'm using GM, at the office. It's very powerful, but its license seems to be a bit expensive only for a personal application.

Regards,

José

 

[JonPatch]

No, worries, José, I appreciate your willingness to help.

Jon

 

[JonPatch]

Alrighty, my understanding is inching forward. Now I know how to extract the coordinates from a geoTIFF. And how to insert them into a TIFF that has been manipulated in photoshop so it georeferenced.

Some questions remain:

1. How do I insert into that geoTIFF the tags that specify the projection/datum, eg state "WGS84"? Resample won't work as I understand it without that.

2. when using GeoTIFFExamine to create a .tfw file, I note the following:

Tie Point, World X: is my latitude in decimal degrees
Tie Point, World Y: is my longitude in decimal degrees
Tie Point, X Pixel: if tie point is not NW corner of image, specify X difference in decimal degrees, otherwise = 0
Tie Point, Y Pixel: if tie point is not NW corner of image, specify Y difference in decimal degrees, otherwise = 0

... then the X Pixel Scale I would presume to be the number of decimal degrees per pixel, and Y Pixel scale the same. Is that correct? If so then the X and Y Pixel Scale numbers would be different. If I make them different, I find that ERDAS ViewFinder crashes when loading the image.

3. Maybe I'm a crazy person trying to do this without Global Mapper, but with a bunch of different tools. Is there a tutorial written on how to go from an image which is a .TIFF with no tags, that is in the correct projection, and that we know the corner coordinates, to a georeferenced image that resample will process happily?

Jon

 

[rhumbaflappy]

Hi Jon.

I've made up images and saved them as TIFF type. Then I simply used Geotiffexamine to tag the coordinates of my choosing... and resample works just fine.

I think what happens is that resample must not find tags of projections other than lat-long, WGS84. But if no projection-datum tag is found, I think the resample works just fine.

So any image can be used to make a geotiff for resample.

But do you know you don't need to make a geotiff. A regular tiff would also work, as would a bitmap, or targa ( .tga ). In those cases you'd need to specify the bounds and pixel spans just like an old-style INF file.

Dick

 

[JonPatch]

Hi Dick,

I can see I'm making assumptions about why resample is not working on some images. It was telling me "projection data not found" or some such message, and not successful.

I think I'm wanting to be elegant and embed the data in the TIFF rather than using the INF parameters. But since resample is still choking on some (most) images I try, that may be the way to go ...

Thx,

Jon