AVIATIONTOOLBOX: How do you like your maps stitched?

[As I mentioned earlier, I'm going to use this "AVIATIONTOOLBOX" keyword
so that those who'd like to keep up with these projects can do so easily
without the annoyance of using a mailing list and others can easily skip/
killfile them. If you have better suggestions, please feel free to send
them to me directly or hash it out here. I don't plan to always post to
comp.infosystems.gis but I thought this topic would be good to address
there.]

Recently I've been working a lot on manipulating the FAA sectionals I
purchased.
http://aviationtoolbox.org/raw_data/FAA_sectionals/
I've been amazed by the hundreds of people who have downloaded this data.
There's apparently some interest in it so I'd like to solicit input on
some of the projects I'm pursuing with the data.

Right now I'm working on breaking up the maps into easily-used subimages.
I do this (using GDAL) by hacking off all of the stuff around the maps,
converting them to RGB, warping them to match the Wichita sectional, and
then cutting them into chunks.

The tricky part is that the maps overlap. For the North and South sides,
this usually isn't a problem. Different regions however can depict the
same geographic area quite differently. Choosing how to display these
areas of overlap isn't obvious to me.

I've made a couple of example attempts. The first
http://aviationtoolbox.org/tmp/chunk_furthest.jpg
simply chooses whatever pixel was furthest from the nearest edge in the
original map. That does a fairly good job, but there is some information
that is just lost - it's near the edge on both maps, so it isn't shown at
all. (See the "PINONCANYON0 MSL" area on Denver/Wichita border.)

The next
http://aviationtoolbox.org/tmp/chunk-blended.jpg
is a bit more complicated. The weighting of the pixels fades toward the
edges so that the maps blend into each other. Sometimes this looks much
better to me, but sometimes it looks like I'm trying to read in
turbulence. (See the Dalhart airport/VOR.) The big advantage is that no
information is lost.

Another possibility I'm going to pursue is prioritizing the colors so
that some colors (blue, maroon, black, ...) take complete priority over
more "backgroundish" colors. That could make for some strange looking
airports (See Miller dear Dalhart.) but I think it might look "cleaner"
without information loss.

So...anyone have strong feelings about how this should be done?

Thank you.

--kyler

On Sat, 29 Nov 2003 22:09:24 GMT
Kyler Laird wrote:

[As I mentioned earlier, I'm going to use this "AVIATIONTOOLBOX" keyword
so that those who'd like to keep up with these projects can do so easily
without the annoyance of using a mailing list and others can easily skip/
killfile them. If you have better suggestions, please feel free to send
them to me directly or hash it out here. I don't plan to always post to
comp.infosystems.gis but I thought this topic would be good to address
there.]

Recently I've been working a lot on manipulating the FAA sectionals I
purchased.
http://aviationtoolbox.org/raw_data/FAA_sectionals/
I've been amazed by the hundreds of people who have downloaded this data.


How do you and others mean to use these charts? Laptop in the plane?
Just for reference during flight planning? Print them and take them along?



R. Hubbell


There's apparently some interest in it so I'd like to solicit input on
some of the projects I'm pursuing with the data.

Right now I'm working on breaking up the maps into easily-used subimages.
I do this (using GDAL) by hacking off all of the stuff around the maps,
converting them to RGB, warping them to match the Wichita sectional, and
then cutting them into chunks.

The tricky part is that the maps overlap. For the North and South sides,
this usually isn't a problem. Different regions however can depict the
same geographic area quite differently. Choosing how to display these
areas of overlap isn't obvious to me.

I've made a couple of example attempts. The first
http://aviationtoolbox.org/tmp/chunk_furthest.jpg
simply chooses whatever pixel was furthest from the nearest edge in the
original map. That does a fairly good job, but there is some information
that is just lost - it's near the edge on both maps, so it isn't shown at
all. (See the "PINONCANYON0 MSL" area on Denver/Wichita border.)

The next
http://aviationtoolbox.org/tmp/chunk-blended.jpg
is a bit more complicated. The weighting of the pixels fades toward the
edges so that the maps blend into each other. Sometimes this looks much
better to me, but sometimes it looks like I'm trying to read in
turbulence. (See the Dalhart airport/VOR.) The big advantage is that no
information is lost.

Another possibility I'm going to pursue is prioritizing the colors so
that some colors (blue, maroon, black, ...) take complete priority over
more "backgroundish" colors. That could make for some strange looking
airports (See Miller dear Dalhart.) but I think it might look "cleaner"
without information loss.

So...anyone have strong feelings about how this should be done?

Thank you.

--kyler

"R. Hubbell" writes:

How do you and others mean to use these charts? Laptop in the plane?
Just for reference during flight planning? Print them and take them along?

Yes.

I'm mostly trying to make the data easily acessible so that others can
be creative. I think they'll be used in ways I haven't even considered.
Already I know of one person using them for flight planning, in-flight
moving map display, and tracking search and rescue operations.

--kyler

On Sun, 30 Nov 2003 02:09:26 GMT
Kyler Laird wrote:

"R. Hubbell" writes:

How do you and others mean to use these charts? Laptop in the plane?
Just for reference during flight planning? Print them and take them along?

Yes.

I'm mostly trying to make the data easily acessible so that others can
be creative. I think they'll be used in ways I haven't even considered.
Already I know of one person using them for flight planning, in-flight
moving map display, and tracking search and rescue operations.

Well I have to say I'm not sure how they could be used as a moving map.
Wouldn't they need to be vector graphics with the some reference?
Or is it possible to create geo references and plot courses and
positions?

I guess I'm thinking out loud but if you know it'd be great to hear how
they are being used. i.e. the technical side
It's really amazing how clear the images are

R. Hubbell



--kyler

"R. Hubbell" writes:

Well I have to say I'm not sure how they could be used as a moving map.
Wouldn't they need to be vector graphics with the some reference?

No, raster graphics are plenty fine for moving maps. Sure, there
are some disadvantages, but since the sectional charts seem to be
maintained in hard copy, I don't expect much beyond raster
graphics soon.

('course if you want to make your own vector graphics, the data is
available.)

Or is it possible to create geo references and plot courses and
positions?

They're already GeoTIFFs.

--kyler

I've downloaded the sectionals, and have brought them into Oziexplorer
moving map program ($75 download.) Also downloaded waypoints from one of
several aviation waypoint generators and imported them into Ozi. After
geo-referencing the map files, the waypoints line-up over the airports/vor's
etc., so one can then create routes.

So far, I haven't used it in the plane, but used it in the car and it seemed
to work fine.

Many thanks to Kyler.

"Kyler Laird" wrote in message
...
"R. Hubbell" writes:

Well I have to say I'm not sure how they could be used as a moving map.
Wouldn't they need to be vector graphics with the some reference?

No, raster graphics are plenty fine for moving maps. Sure, there
are some disadvantages, but since the sectional charts seem to be
maintained in hard copy, I don't expect much beyond raster
graphics soon.

('course if you want to make your own vector graphics, the data is
available.)

Or is it possible to create geo references and plot courses and
positions?

They're already GeoTIFFs.

--kyler

"Tom Jackson" writes:

I've downloaded the sectionals, and have brought them into Oziexplorer
moving map program ($75 download.) Also downloaded waypoints from one of
several aviation waypoint generators and imported them into Ozi. After
geo-referencing the map files, the waypoints line-up over the airports/vor's
etc., so one can then create routes.

What do you mean exactly by "After geo-referencing the map files"? They're
already georeferenced. Is there a format problem/incompatibility?

So far, I haven't used it in the plane, but used it in the car and it seemed
to work fine.

Great! I'm looking forward to doing something useful with them personally
so I especially appreciate hearing that they're working for others.

Many thanks to Kyler.

You're quite welcome.

Thank you for the report.

--kyler

On Sun, 30 Nov 2003 04:18:49 GMT
Kyler Laird wrote:

"R. Hubbell" writes:

Well I have to say I'm not sure how they could be used as a moving map.
Wouldn't they need to be vector graphics with the some reference?

No, raster graphics are plenty fine for moving maps. Sure, there
are some disadvantages, but since the sectional charts seem to be
maintained in hard copy, I don't expect much beyond raster
graphics soon.


Must be a ton of work to maintain and update them.


('course if you want to make your own vector graphics, the data is
available.)

Or is it possible to create geo references and plot courses and
positions?

They're already GeoTIFFs.


There's the magic word. There are plenty of programs and libraries (of
the software kind) for manipulating these files. If you had mentioned
that they were geoTiffs already I must have missed it.


R. Hubbell


--kyler

On Sun, 30 Nov 2003 02:09:26 GMT
Kyler Laird wrote:

"R. Hubbell" writes:

How do you and others mean to use these charts? Laptop in the plane?
Just for reference during flight planning? Print them and take them along?

Yes.

I'm mostly trying to make the data easily acessible so that others can
be creative. I think they'll be used in ways I haven't even considered.
Already I know of one person using them for flight planning, in-flight
moving map display, and tracking search and rescue operations.


FYI, this site has some good tools for wrangling geoTiff. I saw NT, linux,
solaris and Mac binaries on their ftp site too.

http://remotesensing.org/geotiff/geotiff.html



R. Hubbell



--kyler

Well, maybe my terminology is inaccurate, but what I meant to say was, I
load, and calibrate the map image. Basically, I load the map projection
information into the program (i.e., Lambert Conformal Conic, with the
appropriate lat/lon info.) I got this information from one of the HTML files
related to the specific map TIFF.

"Kyler Laird" wrote in message
...
"Tom Jackson" writes:

I've downloaded the sectionals, and have brought them into Oziexplorer
moving map program ($75 download.) Also downloaded waypoints from one of
several aviation waypoint generators and imported them into Ozi. After
geo-referencing the map files, the waypoints line-up over the
airports/vor's
etc., so one can then create routes.

What do you mean exactly by "After geo-referencing the map files"?
They're
already georeferenced. Is there a format problem/incompatibility?

So far, I haven't used it in the plane, but used it in the car and it
seemed
to work fine.

Great! I'm looking forward to doing something useful with them personally
so I especially appreciate hearing that they're working for others.

Many thanks to Kyler.

You're quite welcome.

Thank you for the report.

--kyler