GTFViewer. The GTFViewer is a programsthat allows you to view, manipulate and copy the images into other programs. GeoTiff files are produced by the USGS and other government agencies and they generally contain topomaps and aerial photographs. The program has many features:

LARGE IMAGES. GeoTiff files can be very large and Windows 95/9/Me has trouble handling large bitmap images. This leads memory errors even when the computer has plenty of memory. The GTFViewer uses special routines to minimize the effects of these problems. Under Win NT, 2000 and XP, the GTFViewer can deal with huge images with absolutely no problems. TRIMMING IMAGES. The GTFViewer allows you to trim off parts of the image to get rid of borders and to zero in on specific parts of a map or aerial photograph. This also reduces the size of the file, which can make it more useful for publication or display on the web.

RESIZING. GeoTiff files are often very large, which makes them difficult to handle or view on normal computer screen. The GTFViewer can rescale an image to any size. The program uses special resizing algorithms, which minimize artifacts and loss of resolution. To the right is a simple example that will give you an idea of the power of the GTFViewer. The text on the left shows simple text. The middle image has been shrunk to 70% of its original size using Microsoft Paint. As you can see the text is completely unreadable. The image on the far right was shrunk to the same size using the GTFViewer. As you can see, the text is small but still readable.

MEASURING. Some GeoTiff files contain scaling and location information. As a result, the GTFViewer can measure distances and surface area on maps and aerial photographs. Distances can be measured along curving features such as roads, streams, etc. Area can be measured for irregular shapes such as lakes, cities, etc. Example. In the example to the right, we are mesuring the perimeter and area of reservor near Bogota, Columbia. As you can see, the perimeter is 10.7 miles and the area is 2.5 square miles. PRINTING. The GTFViewer has special features help you deal with printing large images. The images can be shrunk to fit the size of the paper. It also capable of printing full resolution images tiled across multiple sheets of paper.

Getting A Copy. You can download an evaluation copy of GTFViewer by clicking here: Down Load.

Registration. The GTFViewer is shareware software. It is not public domain software, and it is not free software. If you want to use the GTFViewer for any purpose other than evaluation, you must register. Registration costs only $15 and licenses you to use GTFViewer on a regular basis. It also entitles you discounts on printed manuals, special promotions, and mailed notification of updates.

COMPASS Users. Registered users of COMPASS survey software are automatically registered to use GTFViewer.

Registration Options	Cost	Click Here
Individual GTFViewer Registration.	$15.00
Institutional Registration. For  clubs, businesses, institutions, and government agencies.	$25