9 replies to this topic

[benbakelaar]

Does anyone know of any software that can load a raster image (JPEG, BMP, GIF) and you can set multiple "location points" on it (this point = lat X, lon Y), and once you have set enough, you can transform the projection to match, say, WGS 1984 (or any defined projection)?

For instance, this map: http://mapmaker.rutg...APS/NJ_1795.jpg

I could click on, say, 16 points, a square box of 4x4 points, and set lat/lon pairs. Then I could transform it to WGS1984 projection so that I could make a tileset out of it and load it over Google Maps. Of course this is not exact - but I imagine it would be close enough to get the desired result.

[ELeFevre]

Ben,
You can do this in almost any GIS (ArcGIS Arcview seat or Manifold). Be sure and check out Avenza's Geographic Imager plug-in if you have Photoshop CS. They have a 14 day trial to get you started.

[benbakelaar]

Well I have ArcGIS 9.1, but my help file never installed properly! What is the process or tool called? I'm not used to working with raster in ArcGIS, only vector.

[ELeFevre]

Well I have ArcGIS 9.1, but my help file never installed properly! What is the process or tool called? I'm not used to working with raster in ArcGIS, only vector.

Hey Ben,
Try this:
Go to View>Toolbar>Georeferencing. You need to fix that help file! This will set you in the right direction: Georeferencing a Raster Dataset

[Charlie Frye]

Georeferencing as well as Spatial Adjustment (georeferencing is raster, spatial adjustment is for vector) are both ArcView licencing level functionality. Both have toolbars that contain the relevant tools and the help topics are pretty decent as a basis to get started.

In particular the georeferencing allows you to set vectors for stretching the image. As a layer in your map, these are retained and your image will georeference on the fly as you use the map--for large images, this can be slow. Thus, another option is to rectify the image, which is really saying write a new image file based on the transformation and stretching vectors you've specified.

If you don't know your image's coordinate system, there's not much of a way to project it a known projection without some problems. There is a raster project tool, which will project a raster of a known coordinate system to another coordinate system; and there is a tool called define projection, which will assign a coordinate system to a dataset.

Closely related, we added some new raster layer functions at 9.2, one for on the fly orthorectification, as well as on the fly pan sharpening. We also did a on the fly hillshade, but I haven't found it useful for making maps.

Erin pointed out that the Web Help is available, though note that the search engine is different and a little inferior to the one we started using for the Desktop Help at version 9.2--which is by far the best we've ever had.

Another resource would be our functionality matrix, which lists the function an the licensing level--sadly I didn't know we even had such a thing until this morning.

PDF Brochure/Poster view:

http://www.esri.com/...lity-matrix.pdf

PDF letter size text table view:

http://www.esri.com/...matrix-list.pdf

here is the 9.1 version (just in case)

http://www.esri.com/...lity-poster.pdf

[Polaris]

global mapper also offers a reasonably easy way to do this

eric

[benbakelaar]

For web mapping, I just found out that Windows Live Local (via the Virtual Earth SDK) offers a program called MapCruncher which will take numerous input formats (raster and vector) and let you georeference (by points) to their tileset, and then will do all the tile projection matching, warping, slicing and dicing, and even provide you with the HTML necessary to display the results your own server! Plus it gives you an instant preview from inside the program. I did it with a small campus map of my university, and the results were impressive, although to get an "exact" fit you will need to identify many points on the edge of the image as well as in the middle.

I am super impressed... and considering switching from the Google Maps API to the Virtual Earth SDK as my main web platform.

[frax]

related - in ArcGIS 9.1, I have a tiff file that I want to georeference without transforming it - I know the projection, I just want to give it the coordinate references (i.e. I want to create a world file). Using the Georeferencing toolbar, I can only find functionality that resamples the image in the process (even if it does it a little - I am not keen on it).

[Martin Gamache]

Can you not write a tfw with a text editor and set the projection in catalog?
You could also use something like Geotiff examiner to write some of the spatial tags.

[frax]

Martin,

That is actually how I am doing it right now - I am using the georeferencing tools to get the image nicely aligned (which is easy, only needs two points) - then I get the coords for the upper left and bottom right corners, and feed them into an excel sheet. The sheet (attached) is set up to automatically calculate the world file, which I paste from excel to a text file. I just thought there was a smoother way.