Topo Elevation Locations in HDMapper™
Q: How can I find the geographic area covered by my topographic elevation data files, and what files I may be missing?
A: With TAP6.0.2202 or later and a Maintenance Subscription date of November 30, 2007, or later, you can use HDMapper to display the areas included in topo elevation data files.
Note that all values in this example are for demonstration purposes only. You should determine appropriate settings for your application.
This FAQ describes how to display the topo elevation file index information for an area of interest. If you want to display the data available in your TAP system using a map of the entire continental United States, you can download the shapefile and load it into HDMapper as follows
Download the file from the SoftWright site at:
http://www.softwright.com/ftp/shp/SHP_US.ZIP
Unzip the file into the folder where TAP is installed. The shapefiles will be unzipped to a sub-folder SHAPEFILES\USA\US.
Load the desired file (probably the file US48_States.SHP to show state boundaries) into HDMapper.
Topographic elevation data files used in TAP must be indexed in order for the software to find the files. That index can be used to draw rectangular areas that show the extent of the files. Note that most data formats supported by TAP include the possibility of missing or void or null data values. The function described in this article draws the outline of the area covered by the file, but does not indicate if some of the elevation values in the file are missing.
For example, suppose you have a map displayed as shown. Click the “Create layer file for Topo Data Locations” button:
You will be prompted for the index file to read and the layer shapefile to write.
On most TAP systems, the only available index file is the SWSRCIDX.DBF file located in the “FileScript” folder where TAP is installed.
You can use the browse (“…”) button to specify the folder and file name you want to write for the layer shapefile.
If the “Draw map” checkbox is marked the file will be added to the current map. If the box is not checked, the file will be created and can be used later.
When you click Start, if the file already exists you will be prompted to decide if you want to replace the existing file.
If you do not want to replace the existing file, cancel the operation and specify a different file name.
When the shapefile has been created, a dialog box is displayed:
When you click OK (if the “Draw Map” box was checked) the layer will be added to the map.
You can double-click the layer in the index to change the properties.
For example, on the Layer form you can double-click the symbol for the layer:
When the Symbol Settings form is displayed, you can use the Fill pulldown list to set the value to “Diagonal Cross” or “Transparent” or another setting that will provide the image that will be helpful to you. Be sure the “Outline” box is checked, and set the color and width of the outline as desired”
Click Continue to close the “Symbol Settings” dialog box.
Click Continue to close the “Layer” dialog box”
The data file areas will be displayed on the map:
You can use the Map Info button to display the information about the data files by clicking on the map:
Note that if there are overlapping files, the Map Info button may not display all of the information for all of the files.
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Copyright 2007 by SoftWright LLC