Yes , do the Right Thing and pay attention to accuracy at all levels
The accumulation of error as data is repeated analyzed and projected for multiple purposes. Carefully integrate your mapping grade GPS data into a GIS. M. Dennis makes a strong argument for Doing The Right Thing and treating data with utmost eye for accuracy.
1. Historical perspective
In May 2000, deliberate degradation of GPS accuracy (Selective Availability) was turned off. With this new found accuracy, besides more ‘practical applications’, geocaching was born. Anyone with GPS and internet connation could ‘hide’ and ‘find’ with recreational GPS.
2. User expectations have soared
Today we take mapping programs, widely available submeter accurate imagery and online mapping data and resources for granted. Most mobile devices, cellular phone and even cameras are now GPS enabled.
3. Do mm and cm really matter?
The answer depends on your project and your purpose for collecting the data. Here are some issues to consider.
For recreational purposed like finding a geocache or trail. but when combining ‘good enough’ GPS data with other datasets it can.
Mapping grade GPS now offers sub-meter accuracy at a price only once afforded by survey grade technology.
Also important to think about is what with what other datasets will your project data be analyzed and displayed. In other words, how do you explain to your users why your ‘good enough’ GPS trail data does not line up with the roads displayed on a Google Earth driving tour which features sub-meter, color imagery?
Even at 2 cm/yr with adjustment from Epochs 1997 to current 2012, in 15 years shift will be 30 cm total!