Topographic Change Mapping
Frequently Asked Questions (FAQs)Many of the questions we receive about our Topographic Change Mapping project are similar in nature. Recognizing this, we have compiled this list of Frequently Asked Questions (FAQ). Some of the responses will direct you to contact the NOAA Coastal Services Center directly for more detailed answers.
If I never received the e-mail from LDART, my data file had nothing in it, or LDART didn't work, what can I do?You may have typed your e-mail address incorrectly, or LDART may have a bug. Try your request again, and if you still do not receive any messages, send an e-mail detailing your problem to csc@csc.noaa.gov and type "Attention: TCM Project Scientist" in the subject heading. What do I do if I created a data file with LDART, but it is too large for me to download or work with?Go back to LDART and choose a smaller area, or subsample your data using the "binning" option. Why are the elevation values I downloaded much less than zero (-20 to -40 meters)?The data you downloaded are most likely referenced to an ellipsoid surface. The values you are seeing are about the expected range for that vertical reference frame. To get values that are closer to "0=mean sea level" try either the NAVD88 or NGVD29 datum in the Vertical Datum selection box in the LDART applet. For help with the concept of a vertical datum see the NGS FAQ. What is the binary raster format?The binary raster file format is a simple format that can be used to transfer raster data between various applications. It consists of two files, the IEEE floating-point file and a supporting ASCII header file. The header file must have the same name as the data file, but with a .hdr file extension. The header data includes the following keywords and values:
For example, The nodata_value for the LIDAR ATM data set is -999999. How do I convert binary raster files to ESRI grids in ArcView 3.x?
You may find it useful to download the LIDAR Data Handler. This ArcView® extension provides a set of tools that you may find useful for working with grids. How do I convert binary raster files to ESRI grids in ArcGIS?
You may find it useful to download the LIDAR Data Handler. This ArcView® extension provides a set of tools that you may find useful for working with grids. |