[OSM-talk] New Map Warper

Tim Waters (chippy) chippy2005 at gmail.com
Wed Feb 11 17:35:17 GMT 2009

2009/2/11 Ævar Arnfjörð Bjarmason <avarab at gmail.com>:
> On Wed, Feb 11, 2009 at 1:06 PM, Tim Waters (chippy)
> <chippy2005 at gmail.com> wrote:
>> I'd like to announce the release of the latest Map Warper image
>> rectifier application, designed with OSM in mind.
>> http://warper.geothings.net/
> Firstly thanks for working on this, it's a very useful application
> which makes it very easy to use third-party bitmap maps to import into
> OSM.
>> You may have seen or used the older application, this one has got a
>> few more bells and whistles, including:
>>    * Search for maps.
>>    * Users & "MyMaps". (no need to sign up to use it)
>>    * Image cropping.
>>    * Control Point editing.
>>    * Calculation of RMS errors.
>>    * Export in different formats.
>>    * Activity feeds.
>> More info: http://thinkwhere.wordpress.com/2009/02/10/new-map-warper/
>> Caveats: It will rescale large images (over 1500x1500), but it also
>> makes things work much faster. It is ultra-beta and undergoing active
>> development, so expect bugs and things not to work, but for most uses
>> it should work fine. Let me know if you encounter any such things.
>> If you have any existing WMS links from the older version, they will
>> still work and I've also imported the existing maps, and control
>> points. If you sign up and want to "own" a map you previously
>> uploaded, let me know.
>> Features planned include serving the rectified maps as tiles, adding
>> tags, making maps private, making the KML export better, and
>> incorporating GeoRSS feeds. Again, feel free to drop me a line if you
>> have a good idea for a new feature, or if you'd like to hack on it.
> These new features are very useful, especially the ones to do with
> user accounts, it's nice to have a list of your maps instead of just
> adding them to one giant pool.
> I think the map rectifier is a bit less intuitive than in the previous
> version. I used to be able to double click on either map which would
> add a new rectification point and then do the same with the other map,
> but now one has to switch between the Add point/Move point/Move map
> tools to move around the map. This has the advantage of being able to
> double click on the map in move mode without adding points (and
> probably something else I'm missing). But switching between the
> different modes took me bit longer using this method.

Yes, I'd agree with you there, the reasoning is that people tend to
use double click to zoom in, but I think that double clicking should
make it a bit easier. Will look into it.

> Also, being able to download GeoTiff from the application is a very
> useful feature, but does it also support GeoTiff uploads? That would
> enable moving maps between installations and using this as a easy to
> set up WMS for misc GeoTiff files.

At the moment, I don't think it likes geotiff files that have already
been rectified, but you could try with a small one... Anyhow, the
approach I would take is to strip out any original geo tags from the
image, and so you would have to add a few control points and warp it
It's not really meant to be a WMS host for ready made GeoTiff files,
but I may put a simple upload-a-tif-and-host-it service anyhow, as you
are not the first person to ask for this.
 (JOSM import support for reading geotiffs would rock).

> The biggest disadvantage of this tool is still being limited by the
> size of maps you can upload. I have several ~6000x~5000 pixel maps I'd
> like to have access to over WMS, each around 12 MB[1]. Is there any
> reason for this limitation other than preventing the application from
> taking over resources on your server? Or is it a limitation of some
> library you're working with?

Yes, this is Dreamhost, they have a script that will terminate
processes using a lot of CPU or RAM, so I can add a couple of
restrictions (file size and image dimensions). You may like to have a
look at another deploy over at http://warper.freemap.in for larger
files. We're going to be warping 800mb tifs soon... here, the main
limitation is that you can expect http timeouts for very large


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