GPS systems do not work in indoor environments and when obstacles, like tall buildings, block satellite signals. Dead Reckoning (DR) is a wayfinding technology that can be used to identify locations indoors. It is especially helpful as a tool for working in combination with GPS. When GPS signals are blocked, location based information processing can be passed on to Dead Reckoning systems for analysis and reporting. DR can access geographic data bases similarly to GPS. Accuracy of DR is often better than for current GPS systems. Nano technology breakthroughs hold promise that these DR systems can be as small as one inch cubes, and therefore perfect for wearable computing applications..

DR uses a very sophisticated electronic compass, with mechanisms for calculating speed, position, heading, and distance to destinations (just like GPS). Movement detection systems are also built in (accelerometers, gyros, pedometers). Unlike GPS, Dead Reckoning can also provide vertical coordinates (what floor of a building you are on, for example).

Use of DR technology is spawning the development of indoor maps, "location-based knowledge banks". DR has the potential for use with building blueprints, indoor number systems, and landmarks positions.

An example of dead reckoning technology is the OmniMate under development at the University of Michigan.

Sentient computing refers to indoor sensory systems that track the location of individuals (movement) inside buildings. This could be accomplished in various ways. One system on the market uses fluorescent bulbs as data transmitters. These are sold by a Boston based company called "Talking Lights." Invented by MIT professor Dr. Steven Leeb, this system holds promise as a navigation aid for blind individuals.