Messages

Thanks for both answers.  The technical answer explained a lot of things, but the magic answer made it 100% certain.  I also needed to get my terms straight since it has been so long since I learned the terms.  I do not need the terms to read a map and compass, but I do need them to communicate.

I want to repeat the sentiments.  This is a super cool site.

Can somebody explain to me how map projections work in GPS units?  It seems to me you need to do something, like set the GPS unit to the correct map projection before you load the map?  If you do, how do you know the projection of the map you loaded, such as the Ibycus data on this web site.  Or does Mapsource magically handle everything so you do not need to worry about that? 

One more question.  I just got my GPS and tried it yesterday, recorded a route, and changed the projection to the two most common I see (NAD27 and 83).  The position of the route relative to the map seemed to stay the same.  Are GPS units so smart they adjust everything realted to the map projection on the fly or was this a coincidence?

Thanks for the answer.

First, thanks for the additional link.  And I did ask about this in another forum.

And I am mixing two different desires, my desire to have good street data and my desire for good forest road data.  I will take all of your great advice with the street data.  But I am still curious about forest road data.

In wildland fire I have been all over the country, which is why I would like to have access to data that generally accurate over the western states.  But the reality is I have spent 85% of my time Oregon, Washington, and Idaho, and would be happy with accurate data for those states.  

I am getting out of the physical side of fire, which is why all I care about are roads.  My days of going through the woods on a fire are coming to an end, which is why I do not care how accurate the topo data is.  And I will always have a laptop with me which I can pre-load with data.

One thing I did not think about until writing this post is that I can judge forest road data by comparing it to the aerial photos in Google Earth.

And in reality the fire idea is probably a bad idea.  Though GPS units are used extensively for mapping fire data, they are rarely used for navigation.  I assume there is a reason.  But a wildlife biologist I work with has been working in this area for 20 years, and when I went out him he used his GPSMAP 76-CSx to navigate the roads.

Basically I would like to get as complete possible logging/fire/dirt road information, without spending more money then needed.  I see three options, Garmin's 1:24,000 maps, Garmin's 1:100,000 scale maps, and the maps here.  Can anybody tell me how complete these maps are without extensive field testing?  Again the only data I care about is road data. 

Also, long shot. but I have to ask.  Can anybody tell me if City Navigator has good wildland road data?

My only experience is with a friend's GPS while in the coast range of Oregon, where Gramin's 1:100,000 maps have very complete road data. If the road data is that good everywhere, I would prefer to purchase the larger scale and get more states. Obviously though I would prefer giving a small donation over the cost of Garmin's maps.

Background. I have a Vista HCx that should be arriving in the mail tomorrow. I am asking for use on wildland fire.  Also since I plan on using the GPS with my motorcycle and bicycle, I may also order City Navigator, pending testing of the city road data from this site.

Thank you for your answer.