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Frequently Asked Questions

Q: Why do I get an error when trying to click on the link to access ESDI?
A: This is usually caused by a firewall on your end rejecting outgoing connections on port 8080. Contact your local system administrator to see if connections to this port are not allowed. This can also occur if our application server fails.
Q: Do I have to use ESDI to download your data?A: No, you can access the FTP servers directly at ftp://ftp.glcf.umd.edu. Landsat is stored in the glcf/Landsat directory. You can also download ESDI layers for searching in your own GIS application.
Q: I'm looking a specific scene and I can't find it in ESDI or on your web pages. Do you have it? Can you upload it for me?
A: No. All data that we add to our archive are obtained through free sources or from data donations.
Q: All files I download end with a .gz extension. What does .gz mean?
A: Files that end with a .gz extension have been compressed using GNU zip and must be uncompressed. For Windows, use WinZip, for UNIX use gzip, and for Mac use Stuffit Expander.
Q: When I try to download a data file, why does it dump the file out as text in the browser window instead of saving it to my hard drive?
A: This usually happens with files that have been compressed with gzip (.gz file extension). If this happens, your browser isn't configured to handle that file type and uses ASCII mode for downloads by default. You can either right click on the link (or relevant operation on non-Windows platforms) and choose "Save As..." or add a new MIME-type in your browser settings to recognize gzip files. The MIME-type should be listed as application/x-zip-compressed for suffixes with gz.
Q: I downloaded a gzip file, but why is the .gz extension missing?
A: Your browser or FTP client automatically uncompressed the file for you. The data file is now ready for use.
Q: I have no problems using ESDI, but I am having problems when downloading the data files. Any suggestions?
A: If you are behind a firewall, your Web browser or FTP client must support and be configured to use passive transfer mode. Most modern versions should switch to this mode automatically but some versions of Internet Explorer require you to turn this mode on under "Internet Options". If you are on a slow connection, try using an FTP client instead of your web browser to download the files or automating your downloads. When clicking on a scene in the "Preview & Download" screen, a link to the FTP directory is available. Use that link in your FTP client. Our FTP servers support resumable transfers, so use an FTP client that supports this feature. You can also try downloading during non-peak hours (anytime on the weekends or 03:00 UTC to 10:00 UTC on the weekdays).
Q: I am using ArcView, how do I import your imagery?
A: See the File Format Guide.
Q: I am using ArcInfo, how do I import your imagery?
A: See the File Format Guide.
Q: Any tips on importing your imagery into other programs?
A: GeoTIFF files should not present a problem since all the information is embedded in the image header. For the binary files, look for a way to import raw, raster, or binary files. You will need to supply the image dimensions which should be found in the metadata file provided.
Q: My connection is too slow to download the data files. Can I have the files put on media and shipped to me instead?
A: Our data is always free for download, but we can send ship a copy to you for a fee. In most cases, this remains a cost effective solution. Contact us for pricing information.
Q: I've downloaded a data file but why does my computer tell me that it has a virus?
A: Certain virus protection programs falsely indicate that our data files have viruses. For viruses to work, they need run a program by either embedding themselves in other programs, by disguising themselves as a legitimate program, or by overflowing buffers or stacks using known faults in specific programs. Since the data files are not programs and do not disguise themselves as programs, the actual chance of this file containing a virus is extremely low. There is also a chance that the file was corrupted in transit, and while not infected, was flagged as containing a virus. Try downloading the file again. If you think you have downloaded a virus in one of our data files, we can verify the contents of the data on our servers for you. If you still do not feel comfortable using that data, you may discard it.
Q: You provide a great service to the Earth Science community, is there any way I can contribute?
A: If you have data that we do not have, you can always donate a copy to us and we will make it available for everyone to download. You can also help by sending us any comments or feedback. We rely on this feedback to improve the services that we provide. Contact us for more information



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