Thanks, Whats the advantage of vector vs. raster? I'm running windows. So with delorme, they make their own that scale to 24K but dont necessarily have all the info the USGS based systems would have? Then if you want that info, thats where their subscription based map library comes in?
File sizes, I guess this doesnt really matter, whatever gives the best detail. For features, the fly through sounds cool but isnt needed. I'd like it to real time track, show distances traveled, mark camps, I dont know if it would store multiday info but that would be nice. Then when I get back, create an overall track for the entire trip, and export to a .gpx.
I've never had a GPS before, so I dont really know all the features. Thanks for all the help everyone.
Vector vs. Raster: They both have advantages and disadvantages. Raster maps are resolution-dependent, just like a photo would be on your computer. The higher the resolution, the closer you can zoom in to an area of the image without it losing as much quality (getting pixelated). Vector maps are not resolution dependent, so you can scale them easily and the image quality is consistent and good. Raster maps often let you see information that vector maps won't have. One of the most common examples are all of the cool little hand-written notes as well as historic data often shown on USGS topo maps. Things such as the tiniest of structures (like a line shack or a utility building), or maybe a simple note like "Rocky" to indicate where there are a lot of exposed boulders or bald rock features. Vector maps tend not to have this level of detail. On the other hand, vector maps will sometimes have current Forest Service road numbers or other route labels from more modern GIS data surveys, that older topo images won't have. Raster maps are just "pictures' of paper maps, or photo maps, and so you can use
any map anywhere in the world that is on paper, whether it be drawn, or photographed; if it can be scanned into an image, then it can be a raster map. This isn't possible with vector maps, as not every map known to man has been converted into a digital vector model. Vector maps have the advantage of being "smart" because they are not just a picture. Every pixel of what you see is dynamic and can be manipulated to relate information, contain data, perform functions, as well as putting different sets of data on "layers" that can be stacked on top of one another, independently turned off, etc. Vector data can be called upon by the user to see information at a glance - this can be info associated with other things, such as turn-by-turn directions, telephone directories, categories for points-of-interest, etc.
So the bottom line for me, is to try and take advantage of both types if possible.
You mentioned DeLorme in your post above - they use vector maps that mimic the USGS topos, but as you mentioned, you can purchase a subscription to access their raster map library too. The raster maps can be laid over their vector stuff for the best of both worlds. They also use DEMs (digital elevation models) so these scans of paper maps can be "molded" in 3D to show a tilted 3D aspect of the terrain.