May 2008 Archives

You can create them yourself from existing USGS quadrangles. But remember they are only as accurate as the image you are looking at.

1) Download your USGS quads from a site on the internet.  I would recommend using the PASDA site.

(www.pasda.psu.edu)  Next enter usgs in the keyword field. Scroll about half way down the page and

choose the file you want to download.  In this example I will be using 1:24,000 - UTM - Cropped Collars.  Click on FTP Download and download your files.  After you have unzipped the files you are ready to go.

2) Open Map 3D and Raster Design.  Using the program Raster Design, Insert the USGS quad that you just downloaded. 

Under Correlation source: use World File Correlation, this will use the coordinate system that came with your quad.  You will notice another file with the same name as the .TIF.  This file is called the "World" file (.TFW) and is needed to retain the coordinate system of the image.

Click next - next - finish and the image appears in your drawing area.  To know whether or not you inserted the image correctly, you can look at the coordinates at the lower left of the screen.  They should correspond with the coordinates that were inserted with the image.

 3) Next we have to change the image to Bitonal.  Under Image select Image Processing - Change Color Depth, then select the image and choose Bitonal.  The image should change to black and white.

4) One more thing to do is to select Image - Cleanup - Invert so that the contours now appear white.

5) Under Image, select Vectorization Tools - Contour Follower.  There are options to change the colors of the lines.  I suggest you create a new layer called "Contours" in your project to make things more organized.

6) Select a contour from the quad image and a line should be created.  You can also assign an elevation to this line. If the Contour Follower comes across another object while drawing the contour such as a piece of text or other non-contour line, you can add a point manually then continue the contour.  Once the digitizing in complete, you can detach the image.  You are now left with only the contour lines on the Layer "Contour".  If you now want to convert the contours to an SDF or SHP file just go to Export as the file type, select the Contours Layer and Elevation in the properties box.  You can then add the SDF file as a data file where you can stylize the contours and display their elevations by the data table.

There will be a new Map 3D Blog coming soon.  This blog will share information about Map 3D along with some tips and tricks of the software.  

Right now for anyone looking for good Geospatial data in the state of Pennsylvania, here is a website for you:

http://www.pasda.psu.edu

There will be much more information to follow.