Cannon wrote:ForeFlight does have great terrain resolution, but it's only useable with an Internet connection, and it's not technically an aviation layer...Why the street map has FAR superior terrain resolution has always baffled me. Inexplicably I can't download the very good and useful (for backcountry flying) street map database, but I can d/l the low res aviation version.
Hence the feature request.
In order to have Off-line Hi-Res terrain maps the data must be vector based, not raster. This is an over simplification but Vector images are based on math, storing image information based on coordinates, kinda like paint pixel X1 thru X100 blue. Whereas Raster images store the actual image for pixels X1, X2, X3, X4, X5, X6, X7, etc.
The terrain data the FAA has is in vector format, they convert it to raster and that's the data they provide to Foreflight (and others) which is why the resolution is so poor when zoomed in to a useful level.
Garmin is using a vector product, from where I don't know. Maybe from the same company that provides terrain data to the FAA. Perhaps a company like Delorme? Garmin's VFR map has much better definition in Alaska then in the Lower 48. I'm sure for the obvious reasons. The vector data remains much sharper when you zoom in because the image redraws itself (math). Garmin could provide that same high resolution in the Lower 48 if they wished.
Foreflight's street map is a raster image, which is why an internet connection is required to use it. The file sizes are too large to be stored locally.
The good news for us is the vector data exists. We just need it implemented in high resolution, in the Lower 48 as well as Alaska. With an "Aviation Layer" over it. That is my top feature request to Foreflight.