# TopoVista 4.0 Release Notes

This is version 4.0 of the TopoVista package. It includes:

- A viewer that displays 3-D perspective images of a digital elevation model.
- Servers that can transmit data to remotely located viewers.
- Conversion utilities for preparing data from USGS files.
- Miscellaneous other related programs.

The TopoVista package also includes the FTN token service, with which the viewer program can interact to find servers or file paths. That part of the project is no longer under active development.

For more information about TopoVista see the website at www.cs.arizona.edu/topovista. Please send problem reports and other e-mail to topovista@cs.arizona.edu.

This is free software. The f123 directory is based on code from the US Bureau of Land Management and is in the public domain. All other components are covered by the statement in this license.

## Known problems

For systems with an nVidia graphics card, TopoVista's use of OpenGL can crash the X server. The fix is to download and install the driver from the nVidia website, www.nvidia.com/object/linux.html.

In the overhead window, grid lines between tiles are not visible on some systems.

In the perspective window, drawn paths change color randomly.

Tiles larger than 256×256 (`tvconvert -h`) contain data records that are too large to transmit via the TVRP protocol. One residential broadband connection of ours can't reliably transmit tiles larger than 128×128.

## Release history

Version 1 of TopoVista (June 30, 1997) displayed DEM files using a right triangular irregular network and a quadtree-like data structure.

Version 2 (March 28, 1999) used a complicated perfect-hashing scheme to minimize memory.

Version 3 (December 16, 2000) returned to the quadtree-like structure to achieve faster drawing speeds. Other speed gains came from better use of OpenGL's graphic primitives. Xiangyu Zhang added smooth surfaces and the ability to display GPS tracks.

Version 4 (October 28, 2003) now uses preprocessed data in custom format. Tiles can be loaded over a network using HTTP protocol or TopoVista's own TVRP protocol. "Flight path" animation has been added.

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