[Gvsig_english] Importing a raster image with gvSIG Mobile
Juan Lucas Dominguez Rubio
jldominguez at prodevelop.es
Mon Apr 4 08:40:45 CEST 2011
Hello,
I used gdalwarp with the -tr param to change the resolution.
The extent changes slightly due to roundings, I think, but the difference is in the order of the decimeters, which is less than the width of a pixel:
Corner Coordinates:
Upper Left ( 9.1256726, 53.4908082)
Lower Left ( 9.1256726, 53.4750997)
Upper Right ( 9.1744405, 53.4908082)
Lower Right ( 9.1744405, 53.4750997)
Center ( 9.1500566, 53.4829539)
Corner Coordinates:
Upper Left ( 9.1256726, 53.4908082)
Lower Left ( 9.1256726, 53.4751060)
Upper Right ( 9.1744369, 53.4908082)
Lower Right ( 9.1744369, 53.4751060)
Center ( 9.1500548, 53.4829571)
The width/height ratio of the image has changed of course, because the pixel resolution has changed only in one of the axis (the X axis).
Regards,
Juan Lucas Domínguez Rubio
---
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/>
---
________________________________
De: gvsig_internacional-bounces at listserv.gva.es en nombre de Marcel Schoolmeesters
Enviado el: vie 01/04/2011 14:56
Para: Users and Developers mailing list
Asunto: Re: [Gvsig_english] Importing a raster image with gvSIG Mobile
Hello,
google coordinates are EPSG:3785, I think? (old name: EPSG:900913) - That was the easiest way to get coordinates. I have used the map for u-center (from u-blox), because of using that application for testing last year. So I easily could lookup zthe upper edge. I did not have any Desktop GIS installed, perhaps I should do that ;) but I will need a map of the region with identical points, don't I? or is it possibvle to transform by click and enter coordinates?
Concerning your new map image: Did you change/rescale the image? it is not the same anymore, so the new worldfile cannot be compared.
As mentioned before, the image is not in EPSG:4326 obviously, otherwise it would not have to be resized by gvSIG Mobile ;) and the ratio is not really small, I think...it is rather 0.5 in height or something surround it?
Regards,
Marcel
Am 01.04.2011 09:22, schrieb Juan Lucas Dominguez Rubio:
Hello, I have realized that in your JGW file the first and fourth parameters dont have the same absolute value:
1.073E-05
0
0
-6.352E-06
9.125678
53.490805
This is not wrong, but maybe the application is not dealing well with it.
To create ECW images, I have used FWTools http://fwtools.maptools.org <http://fwtools.maptools.org/>
- install
- Start the command-line terminal from the new icon
- move to the folder where the files are (cd ...)
- type something like:
gdal_translate -of ecw jpg-map.jpg ecw-map.ecw
(JPG and JGW files in the current folder)
I have recreated the JPG and JGW to have the same absolute value in the first and fourth parameters:
https://correo.prodevelop.es/descarga/gvsig/mobile/new_map.zip
Try that one and see if the image is ok now.
More info:
http://www.gdal.org/gdal_utilities.html
http://www.gdal.org/ogr_utilities.html
************
Apart from that, this is another consideration not related to the previous problem:
How did you create that image? Your original JPG seems to be using a projected SRS (like Google's EPSG:900913 or the German EPSG:3146X).
Did you simply compute the coordinates in EPSG:4326 of the corners and wrote the JGW file by hand? That would not be correct because there is not a linear relation between those SRS (in other words, the "rule of three" does not work with them). In this case, the error would be not visible because it's a small area (so actually that would be a simple, valid approximation), but it's always better to do a proper reprojection with gvSIG or FWTools, for example.
Regards,
Juan Lucas Domínguez Rubio
---
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/>
---
________________________________
De: gvsig_internacional-bounces at listserv.gva.es en nombre de Marcel Schoolmeesters
Enviado el: jue 31/03/2011 20:36
Para: Users and Developers mailing list
Asunto: Re: [Gvsig_english] Importing a raster image with gvSIG Mobile
Hello,
well, I have created the image for myself with google coordinates :-) and I've checked the coordinates of the image and of the cursor...of course....so definitely, it is the image, which is not scaled correctly each time, you can see when looking at those screenshots. The image must be compressed in height (using EPSG:4326) because of the location at 53° N...
I've checked the ECW and it looks and works fine,....can you tell me the commands to create an ecw-file from worldfile? it is a commandline tool, right?
And of course, you mention the "lot of things" the application is doing while zoom or pan....but the image is even not compressed in height being shown the first time (without any zoom)
Well, I think that should be checked...if yomebody got time...it is not important to me at the moment...it might be nice to show some bugs, too :-) but don't know if it is planned to change in gvsig mobile 1.0?
Regards
Marcel
Am 31.03.2011 19:10, schrieb Juan Lucas Dominguez Rubio:
Hello,thanks for the files.
I mean that when you do zoom and pan in gvSIG Mobile, the application does a lot of little things in order to draw the image using as little memory as possible, and if one of those steps is wrong, then the image might be misplaced, but I have never noticed this.
I remember that there is a little bug that causes the GPS arrow to be misplaced when you do some zoom and pan: until the next GPS coordinates arrive (and refreshes the GPS arrow), it can be misplaced. Maybe that's the problem you noticed? Is the arrow misplaced even after you have received several new GPS coordinates?
To find out who is misplaced (the image or the arrow) you can load a shapefile (which always is ok, I think).You can download some ECW and SHP of Bremenvorde from here:
https://correo.prodevelop.es/descarga/gvsig/mobile/
The files called "...31467..." are in EPSG:31467, in case you prefer those. I created them with GDAL and OGR, so I think they have a little error of 1 or 2 meters (which I think is not a problem in this case).
So if you load the JPG, then the SHP and use the GPS, what happens?
If the SHP and the JPG are consistent and the GPS is misplaced, then there is a bug related to the GPS arrow (temporarily? always?)
If the GPS and the SHP are consistent and the JPG is not, then there is a problem with the WKR driver.
Regards,
Juan Lucas Domínguez Rubio
---
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/>
---
________________________________
De: gvsig_internacional-bounces at listserv.gva.es en nombre de Marcel Schoolmeesters
Enviado el: jue 31/03/2011 17:54
Para: Users and Developers mailing list
Asunto: Re: [Gvsig_english] Importing a raster image with gvSIG Mobile
Hello.
I know those performance problems. But if the transformation is performed, it should not be wrong I think :) better would be an error message which tells the user that the image is too big or something...
I cannot upload the image (25MB *.png or 5MB *.jpg), but I have uploaded the jpg to rapidshare, instead. (The png file is about 2MB too big, it won't even be loaded, so I did not upload it)
JPG: http://rapidshare.com/files/455277713/jpg-raster.zip
ECW: http://rapidshare.com/files/455279357/ecw-map.ecw
I have compressed the file to ecw, too, but it is not geo-referenced, I think. I tried AU ECW Compressor...because the manual says, it will add geo-information...but it doesn't....not from an extra worldfile.
Well, to load the worldfile of the JPG, you need to change the getWorldFileExtensions() in WKFRasterDriver.java, I think. Or change the extension to *.wld... but I'm sure, you know. (however, jgw seems to be the default one, isn't it?)
Regards,
Marcel
Am 31.03.2011 17:04, schrieb Juan Lucas Dominguez Rubio:
Hello,
When zooming in and out with a non-ECW image, the app performs some shift and clip operations to minimize the amount of memory needed. I have never seen any strange bevavior there, but there might be a bug, yes.
gdal_translate (FWTools) is free and creates faster, more reliable ECW images.
which format are you using?
can you send the image to the list? (with the georef. file if it's not a ecw file)
Regards,
Juan Lucas Domínguez Rubio
---
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/>
---
________________________________
De: gvsig_internacional-bounces at listserv.gva.es en nombre de Marcel Schoolmeesters
Enviado el: jue 31/03/2011 16:51
Para: Users and Developers mailing list
Asunto: Re: [Gvsig_english] Importing a raster image with gvSIG Mobile
Hey all,
I've got new interesting findings :-)
* The error of the height of the image does not appear at all when I zoom three times.
* When I zoom twice, the error appears only in the middle of the image, but not when I see the background of the Map! I cannot say exactly,...
* But when I does not zoom or only once...or four times or more... the image is not resized I think...it is the original ratio....
I have got some screenshots, so that you might understand it better :)
Perhaps, it is a graphical bug? I don't know...perhaps, somebody's got an idea? would be cool to be fixed!
Regards,
Marcel
Am 30.03.2011 16:42, schrieb Marcel Schoolmeesters:
Thanks for the explanation.
As I said, the ImageExt values are correct...(y is calculated by _y + _h, I think) .....I have debugged the data flow and everything is understandable up to this function (and afterwards. What the function is doing might be clear, and even the values of the viewRect, too,...after your little explanation, what should be self-evident :-)
However, the final lower/left edge of the picture is not shown at 53.475096504° where it should be, but somewhere at 53.464...and I cannot find the code where this is calculated...(but better to say that I have given up because of so many steps...)
Best regards,
Marcel
Am 30.03.2011 09:32, schrieb Juan Lucas Dominguez Rubio:
Hello,
that method computes the extent of the view when you add the first layer. The app knows the size of the screen and the extent of the layer, and their ratios are different, so you have to do a simple computation to find out the extent of the new view.
Maybe you have misunderstood the extent of a layer and the extent of the view?
When you add the first layer, the extent of the view is the smallest rectangle which contains the extent of the layer and, at the same time, respects the width/height ratio of the screen, of course.
Regards,
Juan Lucas Domínguez Rubio
---
Prodevelop SL, Valencia (España)
Tlf.: 96.351.06.12 -- Fax: 96.351.09.68
http://www.prodevelop.es <http://www.prodevelop.es/>
---
________________________________
De: gvsig_internacional-bounces at listserv.gva.es en nombre de Marcel Schoolmeesters
Enviado el: mar 29/03/2011 21:20
Para: Users and Developers mailing list
Asunto: Re: [Gvsig_english] Importing a raster image with gvSIG Mobile
well, I think the main problem of understanding is in function MapContext.getExtentFromFullExtentAndImageSize() ... I think the new height etc are calculated there?
Am 29.03.2011 21:00, schrieb Marcel Schoolmeesters:
Hello,
I have tried to load a raster image (had to try jpg, because *.png did not even load), but I am getting a wrong position of the extent. Anybody got the same error?
I have tried the debug mode, but there are too many functions to catch on. Perhaps anybody can help?
Somewhere the map origin is changed from the upper edge to the lower edge, that far I could follow, but then the image extent (height) and the origin coords (of Y) has been changed. Why? it seems to be very hard to understand the whole way of building the image at the right place.
However, in attachment the original rectangle and the changed one are shown with their values while debugging...
The lower edge of the final image is positioned between those Y values (@ 53.464) but it needs to be positioned at 53.475....
what is getRasterTansformation() actually doing?
Thanks in advance, if anybody can help. However, that issue should be fixed, I think. The import of PNG is not even possible, as I mentioned before..
Regards
Marcel
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