Data Issues (import, export and projections)

This section deals with question specific to importing / exporting, and projecting data.  For more information on supported for specific formats we recommend reviewing our Generic Database Technology Supported File Formats page.

 

A TIFF file I created in Focus causes ArcMap to crash.  How can I get ArcMap to read my TIFF file?

I want to view my UTM projection in units of feet, not meters. How can I make this switch?

I have exported a .pix raster file to another file format (i.e. geotiff, jpeg, etc.) and when I open the file in another software package, the image appears black. What have I done wrong?

Does PCI support NTv2 datum? It is not listed in the list of available datum's when reprojecting.

I am having difficulty getting my vectors to overlay my imagery. There seems to be something wrong with the projection but I am not sure what?

I have IKONOS data in Geotiff format but each channel is a separate .tif file. How can I combine these into one pix file?

I have imported my tiff file into PCI but now the projection is set to meters. What do I do?

Is there a file size limit for tiff?

When exporting a point layer with x, y and z coordinates from a *.pix file to a DXF file type, my output DXF layer is blank.

I have an ASCII text file containing XYZ point data.  What is the best way to read this data in Focus?

Can you tell me a little bit more about the Math Model support in focus?

Q: A TIFF file I created in Focus causes ArcMap to crash.  How can I get ArcMap to read my TIFF file?

A) The Focus .aux associated with the TIFF file contains ASCII text.  ArcMap is looking for .img overview from the .aux file.  To open your TIFF file in ArcMap you can either delete the .aux file or rename it.

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Q: I want to view my UTM projection in units of feet, not meters. How can I make this switch?

A) In order to accomplish this, you will need to add an entry to your "userproj.txt" file so that you are able to change your UTM projection that is in meters to UTM feet. The following example uses "irvine.pix" which is included with the PCI Demo data on the installation CD.

1."irvine.pix" has a projection of "UTM 11 S E000" assigned to it. You are able to view this information under the "Files Tab" by right-clicking on "Irvine.pix" and selecting "Properties>Projection."

2. In your "Geomatica_v91\etc" directory there is a file named "userproj.txt". To get "irvine.pix" into the feet units, you need to add the following entry at the end of "userproj.txt":

ProjectionName "UTM11Feet" ! or any string to describe the projection
ProjectionDescription ""
ProjectionCountry ""
MapUnits "UTM 11 S E000"
Units "FOOT" ! U.S. Survey Feet

3. Add the above entry into your "userproj.txt," save it and then reproject "irvine.pix" ("Tools>Reprojection") into this new projection.

4. In the Reprojection window you can select this new projection by choosing "Other" from the drop down menu beside the "Earth Model" button and selecting the "User Projection" tab.

5. You can validate this conversion by comparing the eastings and northings of the original "irvine.pix" file and the reprojected output. You should see that the geographic coordinates are the same, but the eastings/northings are in feet.

This example is specific to "irvine.pix." If you have UTM files that are in a projection different from "irvine.pix," for example "UTM 6 N E012," then you will need to add another entry to your "userproj.txt" for this specific UTM zone and ellipsoid.

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Q) I have exported a .pix raster file to another file format (i.e. geotiff, jpeg, etc.).  When I open the file in another software package, the image appears black. What have I done wrong?

A) Focus will automatically enhance a raster file when it is loaded into the viewer. Without this enhancement, many images (especially satellite images) would appear black because only a small portion of the histogram range contains data. If you want to open a raster file that you have exported from Geomatica in another software package, you have a few choices to be able to visualize the image.

1. Permanently enhance the image in Focus

This can be done in Focus by right clicking on the .pix raster layer in the Maps tree list, Enhance, Edit LUTs…, then click on the histogram. After you have applied the enhancement, go to “Save” in the menu bar at the top of the LUT Editor window and select “Save Image w/LUT”. You can save the permanently enhanced image in new image layers (recommended) or overwrite the existing image layers. The permanently enhanced .pix image layers can then be exported to another file format.

2. Use the original Digital Numbers in your other software package

To be able to see the data in another software package, you will need to apply an LUT (perform a histogram stretch) within the program you are using.

Note: You can change or turn off the default enhancement in Focus through: Tools, Options, Layers, default visual enhancement under Rasters.

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Q) Does PCI support NTv2 datum? It is not listed in the list of available datum's when reprojecting.

A) NTv2 is now available on CD from Geomatics Canada and, while NTV1 works well for most areas, NTv2 has a greater density of control points in more highly populated regions of Canada . If you have the NTv2 CDROM and want the PCI software to use it, you would do the following:

1.) Activate the datum code records. In the datum.txt file in the PCI home etc sub-directory (e.g. $PCIHOME/etc/datum.txt), there are four records defined for NTv2. These records are commented out at present and can be activated by removing the exclamation mark at the front of the records.

For example, change...

!"D-86","NAD27 ( Canada , NTv2)","E000"," Canada ","ntv2_0.gsb"

!"D-87","NAD83 ( Canada , NTv2)","E008"," Canada ","ntv2_0.gsb"

!"D-88","MAY76 ( Canada , NTv2)","E000"," Canada ","may76v20.gsb"

!"D-89","NAD83 ( Canada , NTv2)","E008"," Canada ","may76v20.gsb"

To..

"D-86","NAD27 ( Canada , NTv2)","E000"," Canada ","ntv2_0.gsb"

"D-87","NAD83 ( Canada , NTv2)","E008"," Canada ","ntv2_0.gsb"

"D-88","MAY76 ( Canada , NTv2)","E000"," Canada ","may76v20.gsb"

"D-89","NAD83 ( Canada , NTv2)","E008"," Canada ","may76v20.gsb"

2.) Decide where you want the NTv2 files to reside and update the filename accordingly in the four records listed above.

A simple filename (e.g. "ntv2_0.gsb") would be searched for first in the local work account. If no file was found by that name, a search is made for it in $PCIHOME/etc (typically C:\Geomatica_V100\etc).

Variations of simple filenames are acceptable. For example, you could put a pathname in the filename in the datum.txt records noted above.

(e.g. "/usr/etc/ntv2_0.gsb" or "c:\usr\etc\ntv2_0.gsb").

For more information visit Natural Resources Canada Geodetic Survey Division at http://www.geod.nrcan.gc.ca

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Q) I am having difficulty getting my vectors to overlay my imagery. There seems to be something wrong with the projection but I am not sure what?

A) PCI Geomatics supports a number of different vector formats for import. In some cases the import of a projection with the vector files is not supported. However, the geographic location of the vectors will be maintained, the file just won't have a projection associated with it. Please refer to the help under Appendices, Geogateway Formats for a more in depth discussion on which projection parameters are imported with which formats.

For example, if you have a DXF file that has been projected to LCC   E000 and you import it to .pix format, the projection will be set to meters.  In this case, the geographic location of the file stills remains accurate however the projection string needs to be updated back to LCC  E000.

To update the projection string, open the file in Focus and select the FILE tab. Right click on the .pix file in the treelist and select properties and then projection. You will probably notice that the file is set to ‘Meters’.  You can update the projection of you file by simply entering in the appropriate projection string.  You will have to update each vector layer. Right click and select properties for each vector layer and update the projection string accordingly.

Please note that you are not reprojecting the data you are just telling the software what projection the file is in.

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Q: I have IKONOS data in Geotiff format but each channel is a separate .tif file. How can I combine these into one pix file?

A) There are several ways to combine three separate to file to one pix/tif file:

1) In Focus select File, Utility, Import and import one tiff image to .pix file format. Under the file menu proceed to Export, to an existing file. This will bring up the transfer layer panel. From here you can transfer the remaining tiff files to the pix file you just created. The file is ready for processing or you can turn around and use Export, To a new file to export this out to an RGB tiff image.

2) If you are using the Ikonos Model in Orthoengine you can import the file as part of an Ikonos project. The read from CD function will build this file for you during import. Please note you must be license for the Ikonos Model to use this method.

- Start Orthoengine project

- Select “Read from CD” and Select “IKONOS (TIFF,NITF)”

- For the CD image filename, specify one of the input bands

- Request all 4 input channels to read in (R,G,B,NIR)

- Specify an output filename

- Read

3) Use Modeler. Open Modeler and lay down 3 or 4 import modules on the canvas. Select one of the tiff images for each Import module. Lay down a merge module and connect up the import modules. Finally select the export module and set up the output parameters for export (you can set the export type to tiff if you want to keep this file in tiff format). Connect the Merge module to the Export and run the Model. You may also want to add a ViewRGB module just to check your results.

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Q: I have imported my TIFF file into PCI but now the projection is set to meters. What do I do?

A: You probably have TIFF World format, if there is a .tfw file associated with your .tif file then yes you do have TIFF World format and there are a few points you should be aware of. The .tfw file will be read for georeferencing, however the projection will be set to METER as .tfw files do not contain a projection string. When you open the file in Geomatica, you will receive a warning that the image uses METER projection. You will have to reset the projection using the File Properties in the File Treelist: From the File Treelist, right click on the file and choose ‘Properties’. Then choose the ‘Projection’ tab and use the drop down menus to select the proper georeferencing for the file.

Please note that once you assign this projection, it will not be stored if you save the image as a tiff. If you want to save the projection information as well, use a format which can contain this information such as pix.

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Q: Is there a file size limit for tiff? 

A: Yes. TIFF uses 4-byte integer file offsets to store image data, with the consequence that a TIFF file cannot have more than 4 Gigabytes of raster data.

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Q: When exporting a point layer with x, y and z coordinates from a *.pix file to a DXF file type, my output DXF layer is blank.

A: In Geomatica, check the attributes of your point layer. With the point layer opened in Focus, right click on the point layer in the Maps Tab and select View Attributes. In the attribute table the EntityType field should be populated with 'POINT'. If this field is populated with another value, like 'POLYLINE', then the output DXF file will be blank.

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Q:  I have an ASCII text file containing XYZ point data.  What is the best way to read this data in Focus?

You can read in you ASCII points file using the “Import ASCII Table/Points’ wizard from the file | utility menu. 

 

  • File | Utility | ASCII Table/Points Wizard

  • Specify your input ASCII text file

  • Specify the output (to file or display) and data format

  • I you are working with ASCII files that create an output pix file larger than 400MB you will need to break up your ASCII file using the “Ranges” Import option. 

*** Note: If you are using “Ranges” to break up large ASCII data sets for import, you must select “Save” rather than display for the output file in step 3 above.  

  • Click next to move on to step two.  Select your delimiters and ensure that your data preview looks correct. Select next to move on to step 3.

  • Ensure that the data type for your X,Y, and Z fields is either ‘Float’ or ‘Double’ and then specifying your coordinate fields

  • Select Finished

  • If you have had to break up your ASCII file because of the size you would then repeat these steps to read in the rest of your records (for example, the first run you would select records 1-5,000,000 and the second time around you would select 5,000,000-10,000,000 as your input record range in step one of the wizard).

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Q) Can you tell me a little bit more about the Math Model support in focus?

A) Math model is a mathematical relationship used to correlate the pixels of an image to correct locations on the ground accounting for known distortions.  Math Models often come with QuickBird, Ikonos, and Orbview imgery.  You can also export a Math Model in Orthoengine and use it when viewing Focus imagery.

It is important to note that displaying imagery with an associated math model in Focus DOES NOT geomatrically correct your imagery.

In the Math Model Area the image is displayed without correction in the viewer, but accurate ground coordinates are calculated for each pixel using the pixel and line coordinates, the math model, and the digital elevation model (DEM), or an approximate elevation value that you provide.

The advantage of using the math model is that you can display geocoded coordinates, overlay geocoded vectors, and digitize geocoded three-dimensional vectors on the raw image instead of going through the potentially time-consuming, labor-intensive process of orthorectifying or geometrically correcting the imagery. This process is also known as mono-restitution.

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