AVIATIONTOOLBOX: How do you like your maps stitched?

"Tom Jackson" writes:

What do you mean exactly by "After geo-referencing the map files"?

Well, maybe my terminology is inaccurate, but what I meant to say was, I
load, and calibrate the map image.

Nope, your terminology is dead on.

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.

Stop doing that! The sectionals are already GeoTIFFs. The FAA has already
done all of that work for us. (They guarantee 2 pixels RMS error, but I've
found distortions much greater than that.)

I'm also working on making more easily-digested chunks of data. If you're
in the mood to burn some time and bandwidth, you can watch my progress.
http://aviationtoolbox.org/munge/mosaic.cgi
Just change the extension to ".tif" on any of the images if you want a 5000
by 5000 uncompressed GeoTIFF.

(I need to tweak my edge-detection algorithm. When I do, I'll clear those
images and start over but you're welcome to try it anyway.)

--kyler

Maybe I'm missing something -- I'll quickly walk you through what I do in
Oziexlporer:
After launching Oziexplorer, I go to the "file" menu, and select "load and
calibrate map image"
This loads the image, but requires that I supply additional data in order to
calibrate the image.

There is an additional menu option to "import map", however, GeoTIFF isn't
an option.

The help screens indicate the following:
*******************help text*****************************
Geotiff
OziExplorer can extract the georeference information from Geotiff files but
it only knows how to decode the information if it is from a known source. At
this stage only the georeference information in the USA USGS DRG Geotiffs
can be decoded.

The ability to decode other sources of georeference information in Geotiff
files will be added on an as need basis where it is possible to do so.


Converting Geotiff Image Files

Some Geotiff Image files are in the 24 bit color format. OziExplorer can
read 24 bit color TIFF files but must load them fully into RAM instead of
paging them from disk as it does with 8 bit color TIFF mages. For large
images this requires a lot of RAM.

If you convert these files to 8 bit color the Geotiff georeference
information is lost.

This document describes a technique to save the georeference information and
to then put it back into the file.

You need

Software to convert the Geotiff image from 24 bit to 8 bit color. Paint Shop
Pro (www.jasc.com) works well.

The Tiff Utilities available from the Utilities section of the OziExplorer
web site (www.oziexplorer.com).

**************end of help text********************

Perhaps the developer of Oziexplorer needs to add these types of files to
its list of "known" types. I will e-mail them.


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

What do you mean exactly by "After geo-referencing the map files"?

Well, maybe my terminology is inaccurate, but what I meant to say was, I
load, and calibrate the map image.

Nope, your terminology is dead on.

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.

Stop doing that! The sectionals are already GeoTIFFs. The FAA has
already
done all of that work for us. (They guarantee 2 pixels RMS error, but
I've
found distortions much greater than that.)

I'm also working on making more easily-digested chunks of data. If you're
in the mood to burn some time and bandwidth, you can watch my progress.
http://aviationtoolbox.org/munge/mosaic.cgi
Just change the extension to ".tif" on any of the images if you want a
5000
by 5000 uncompressed GeoTIFF.

(I need to tweak my edge-detection algorithm. When I do, I'll clear those
images and start over but you're welcome to try it anyway.)

--kyler

"Tom Jackson" writes:

Maybe I'm missing something -- I'll quickly walk you through what I do in
Oziexlporer:
After launching Oziexplorer, I go to the "file" menu, and select "load and
calibrate map image"
This loads the image, but requires that I supply additional data in order to
calibrate the image.

It doesn't sound like you're using a TIFF.

There is an additional menu option to "import map", however, GeoTIFF isn't
an option.

Is "TIFF" an option? A GeoTIFF is just a regular TIFF with some standard
tagged data.

OziExplorer can extract the georeference information from Geotiff files but
it only knows how to decode the information if it is from a known source. At
this stage only the georeference information in the USA USGS DRG Geotiffs
can be decoded.

Oh...hmmm...that's a strange limitation.

The ability to decode other sources of georeference information in Geotiff
files will be added on an as need basis where it is possible to do so.

O.k., so OziExplorer is kinda dumb right now. Looks like you get to do it
manually for awhile.

Converting Geotiff Image Files

Some Geotiff Image files are in the 24 bit color format. OziExplorer can
read 24 bit color TIFF files but must load them fully into RAM instead of
paging them from disk as it does with 8 bit color TIFF mages. For large
images this requires a lot of RAM.

The sectional maps from the FAA are 8-bit color (palette). I convert them
to 24-bit (RGB) when I mask them. The chunks I build are 24-bit.

If you convert these files to 8 bit color the Geotiff georeference
information is lost.

This is just another limitation of OziExplorer. Changing the pixel
representation has little to do with the ability to hold GeoTIFF data.

I'm planning on making 8-bit versions available but it's easier to
manipulate (warp/scale/blend/...) the data without mangling it in 24-bit
mode. My preference is to wait until the last step to create the 8-bit
images.

Software to convert the Geotiff image from 24 bit to 8 bit color. Paint Shop
Pro (www.jasc.com) works well.

Oh, well sure. *That* will destroy the GeoTIFF data.

Perhaps the developer of Oziexplorer needs to add these types of files to
its list of "known" types. I will e-mail them.

Good luck. I'm sorry I made comments assuming that OziExplorer would
deal with GeoTIFFs sensibly.

--kyler

Please see below from the developer of Oziexplorer - they fixed the software
after I pointed them to your data. It now works amazingly well!
**************************************
Hi Tom,

I released a new version of OziExplorer today which should import your FAA
sectional maps without intervention. Use the Import "All DRG maps on a CD or
in a Folder" option.

Regards
**************************************

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

Maybe I'm missing something -- I'll quickly walk you through what I do in
Oziexlporer:
After launching Oziexplorer, I go to the "file" menu, and select "load
and
calibrate map image"
This loads the image, but requires that I supply additional data in order
to
calibrate the image.

It doesn't sound like you're using a TIFF.

There is an additional menu option to "import map", however, GeoTIFF
isn't
an option.

Is "TIFF" an option? A GeoTIFF is just a regular TIFF with some standard
tagged data.

OziExplorer can extract the georeference information from Geotiff files
but
it only knows how to decode the information if it is from a known source.
At
this stage only the georeference information in the USA USGS DRG Geotiffs
can be decoded.

Oh...hmmm...that's a strange limitation.

The ability to decode other sources of georeference information in
Geotiff
files will be added on an as need basis where it is possible to do so.

O.k., so OziExplorer is kinda dumb right now. Looks like you get to do it
manually for awhile.

Converting Geotiff Image Files

Some Geotiff Image files are in the 24 bit color format. OziExplorer can
read 24 bit color TIFF files but must load them fully into RAM instead of
paging them from disk as it does with 8 bit color TIFF mages. For large
images this requires a lot of RAM.

The sectional maps from the FAA are 8-bit color (palette). I convert them
to 24-bit (RGB) when I mask them. The chunks I build are 24-bit.

If you convert these files to 8 bit color the Geotiff georeference
information is lost.

This is just another limitation of OziExplorer. Changing the pixel
representation has little to do with the ability to hold GeoTIFF data.

I'm planning on making 8-bit versions available but it's easier to
manipulate (warp/scale/blend/...) the data without mangling it in 24-bit
mode. My preference is to wait until the last step to create the 8-bit
images.

Software to convert the Geotiff image from 24 bit to 8 bit color. Paint
Shop
Pro (www.jasc.com) works well.

Oh, well sure. *That* will destroy the GeoTIFF data.

Perhaps the developer of Oziexplorer needs to add these types of files to
its list of "known" types. I will e-mail them.

Good luck. I'm sorry I made comments assuming that OziExplorer would
deal with GeoTIFFs sensibly.

--kyler

"Tom Jackson" writes:

Please see below from the developer of Oziexplorer - they fixed the software
after I pointed them to your data. It now works amazingly well!

Impressive! I'm still puzzled about why they couldn't handle the GeoTIFFs
without special intervention, but I like that they fixed it quickly.

BTW, I've finally completed a "chunking" run of all of the sectionals using
the "blend" algorithm. I still don't like the way it looks, but I hope
others will make suggestions.
http://aviationtoolbox.org/munge/mosaic
(Damn! They sure do try to make P-49 obvious, don't they?)

If you select a chunk, you'll get the full-size (5000x5000) version of it as
a JPEG (in another window - always the same one). Change the extension to
".tif" for the GeoTIFF. (Yes, this is just for testing.)

The TIFFs compress about 40%. I should be able to do even better if I
convert them back to 8-bit (palette) images. More later...

It's fun browsing the sectionals. I'd never had one with the note
"APPROXIMATE LIMIT OF PACK ICE THROUGH MARCH".
http://aviationtoolbox.org/munge/chunked/chunk_8_5.jpg

--kyler

In article ,
Kyler Laird wrote:
BTW, I've finally completed a "chunking" run of all of the sectionals using
the "blend" algorithm. I still don't like the way it looks, but I hope
others will make suggestions.

Wow, I've always wanted one of those. I want to take all the flights I've
ever made and plot them on top.

Shame the colors don't match. Maybe you could use the elevation key that's
on every chart to match between TIFs?

--
Ben Jackson

http://www.ben.com/

Wow... I was thinking of trying to do this a few weeks ago when you made the
sectionals available. The fact that it's all in GeoTIFF seemed pretty cool, but I didn't
quite get around to trying to code something up. How much of a pain will it be to redo
it when new sectionals come up? Will you have to re-edit out the non-map area?

Thanks again,
-Cory

Kyler Laird wrote:
: "Tom Jackson" writes:

:Please see below from the developer of Oziexplorer - they fixed the software
:after I pointed them to your data. It now works amazingly well!

: Impressive! I'm still puzzled about why they couldn't handle the GeoTIFFs
: without special intervention, but I like that they fixed it quickly.

: BTW, I've finally completed a "chunking" run of all of the sectionals using
: the "blend" algorithm. I still don't like the way it looks, but I hope
: others will make suggestions.
: http://aviationtoolbox.org/munge/mosaic
: (Damn! They sure do try to make P-49 obvious, don't they?)

: If you select a chunk, you'll get the full-size (5000x5000) version of it as
: a JPEG (in another window - always the same one). Change the extension to
: ".tif" for the GeoTIFF. (Yes, this is just for testing.)

: The TIFFs compress about 40%. I should be able to do even better if I
: convert them back to 8-bit (palette) images. More later...

: It's fun browsing the sectionals. I'd never had one with the note
: "APPROXIMATE LIMIT OF PACK ICE THROUGH MARCH".
: http://aviationtoolbox.org/munge/chunked/chunk_8_5.jpg

: --kyler

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

writes:

Wow... I was thinking of trying to do this a few weeks ago when you made the
sectionals available. The fact that it's all in GeoTIFF seemed pretty cool, but I didn't
quite get around to trying to code something up.

Have at it. Maybe you'll come up with more creative solutions than mine.
I could really use some different perspectives.

How much of a pain will it be to redo
it when new sectionals come up? Will you have to re-edit out the non-map area?

It's automatic. Once I get the FAA images uploaded, I hit "go" and wait
a couple days.

I posted the process in another thread. (Look for the "AVIATIONTOOLBOX"
keyword. I'd give you the URL but I'm offline in a hospital right now.)

--kyler

I saw the other thread... that's how I caught up with it again. I was mainly wondering about the
non-map part... if it changes you'll have to change your map-null list.

Good work! Not sure how to do the "fading" any better than what you've got. Of course, the *real* way to
do this would be to try to get ahold of the vector-based info from the FAA directly. That'd be sweet.

-Cory

Kyler Laird wrote:
: writes:

: Wow... I was thinking of trying to do this a few weeks ago when you made the
:sectionals available. The fact that it's all in GeoTIFF seemed pretty cool, but I didn't
:quite get around to trying to code something up.

: Have at it. Maybe you'll come up with more creative solutions than mine.
: I could really use some different perspectives.

:How much of a pain will it be to redo
:it when new sectionals come up? Will you have to re-edit out the non-map area?

: It's automatic. Once I get the FAA images uploaded, I hit "go" and wait
: a couple days.

: I posted the process in another thread. (Look for the "AVIATIONTOOLBOX"
: keyword. I'd give you the URL but I'm offline in a hospital right now.)
:
: --kyler

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

writes:

I saw the other thread... that's how I caught up with it again. I was mainly wondering about the
non-map part... if it changes you'll have to change your map-null list.

What map-null list? Do you mean the lower-left corners? I don't think they
are likely to change. At least I'll be *very* surprised if they do.

I would have had the opportunity to test another set but the FAA apparently
screwed up my order and they don't even have any more of the current set. So
I'm waiting for the December series...

Good work! Not sure how to do the "fading" any better than what you've got. Of course, the *real* way to
do this would be to try to get ahold of the vector-based info from the FAA directly. That'd be sweet.

I'm sure they'd like to have it too.

--kyler