Hi Dave (and anyone else interested in this), There's one other request I'd make of TaxiDraw at this point. Is it possible to revisit fetch.cpp, the routines that fetch background images from terraserver-usa.com, and tweak it to enable fetching of better images when terraserver-usa has them available (which, for large city airports, is almost always)?
Here's the problem I'm running into. I brought up the raw data for KSDF, an airport with which I'm very familiar, and sent TaxiDraw off to get a background image from terraserver-usa. It returned with an image that's at least eight years old, with an incorrect number of runways, wrong apron location and runway/taxiway layout and so forth. http://www.speakeasy.net/~cmetzler/KSDF_t1fetch.jpg It's not merely a misalignment problem -- our data for 11/29 is aligned correctly with the image, but the two 17/35 runways aren't present in the image at all. It's an old image, predating a lot of changes and improvement, and it's no surprise that the runway and taxiway layouts are way off. So I went off to terraserver-usa's website and clicked through Advanced Find --> Place --> "Louisville, KY, USA". I then find that they have a direct link to aerial images of the airport, from two separate datasets. One, a dataset labelled "Aerial Photo 6/6/1996", is clearly where TaxiDraw got its info. But another dataset present, labelled "Urban Areas 4/7/2002", is not only more current but goes down to much higher resolution. I picked a point feature at the airport, zoomed down to the same resolution using each of the two datasets, and looked at the URLs for the two images I got. I found that they were exactly the same except for "t1" in the old image, and "t4" in the newer image. Looking in fetch.cpp, I see this: } string urlroot = "\"http://terraserver-usa.com/tile.ashx?"; } string scale = "S=10"; } string scale2 = "S10"; } string type = "T=1"; // Not actually sure what this is - type is a guess } string amper = "&"; I don't know C++ at all, but on a hunch I changed that to "T=4", and bingo: TaxiDraw fetched and built an image from the newer dataset. http://www.speakeasy.org/~cmetzler/KSDF_t4fetch.jpg I suspect that the "T" in the image URLs refers to dataset. And what I'm wondering is whether fetch.cpp can do a test to see if "T=4" data is present and use it if so, or drop to "T=1" data and use that if not. The URL change seems to be stable. Here's what I got for KDTW, with "T=1" -- it fetched old data, missing an entire runway as well as a ton of apron/taxiway that's now present: http://www.speakeasy.org/~cmetzler/KDTW_t1fetch.jpg hacking fetch.cpp to "T=4" fetched a newer image, showing the new runway, its taxiways, the completed new terminal and its apron, and so on. http://www.speakeasy.org/~cmetzler/KDTW_t4fetch.jpg The "Urban Areas"/"T=4" dataset is fabulous, btw -- it goes down to 25cm resolution (TaxiDraw fetches 1 meter resolution images, it appears). I'd recommend just changing fetch.cpp to "T=4", and getting the highest resolution images available; but not all areas are covered by the better dataset. That's why I'm recommending tests -- try to fetch from the higher resolution dataset, and drop down to the lower-res one if the first fetch fails. Would it be possible to implement something like this? The complicated airports are much easier to handle with more current, higher-resolution imaging; and since the complicated airports tend to be in/near big cities, those are just the ones for which the better images will likely be available. Anyway, just an idea . . . -c -- Chris Metzler [EMAIL PROTECTED] (remove "snip-me." to email) "As a child I understood how to give; I have forgotten this grace since I have become civilized." - Chief Luther Standing Bear
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