rjcarr's dashboard

I looked into using ModestMaps for a project that I'm starting and I got great feedback from the admins on this forum, so a huge thanks for that!

I've recently been looking at the somewhat new flash api for google maps and since I had previous experience with the js api it makes an easy transition. My thoughts are (relevant to modest maps):

1) Con: The Google API for flash is more polished and the algorithms seem faster with less errors (nothing to be ashamed of, it is google after all)

2) Pro: The Google API is closed and the MM API is open.

3) Con: I had to make quite a few changes to the MM code to make it work for me. This makes me nervous about handling future upgrades.

So, at this point, I think I'm leaning towards using google maps, but if you need the flexibility of other map providers, or just like the openness of MM, it is highly recommended.

What does giving you image tiles (outside of their intended use) have to do with searching? I'm looking for a solution too, that's why I'm at this thread, but they have every right to limit the access to their tiles. – rjcarr, on July 08, 2008 23:08

Thanks Random ... I'm looking forward to the release. Actually, I'm making as little changes in the core libraries as possible in anticipation of the next release.

I went down the road of extending the parts I needed to change but it wasn't as easy as I expected.

PS -- I like that setting up proxies or adding addons is easier for you than looking at a firefox built-in URL request applet. :)

Modest Maps is just a map tile viewer ... it doesn't have any intrinsic zoom level.

Thanks for the quick reply ... I don't assume there is any machinery for version numbers in yahoo providers? Maybe a generic version number getter is in order for all providers?

As for the proxy, and getting the requested URLs, can't you just use the Tools -> Page Info -> Media in Firefox? Safari has something similar in Activity, I think.

Hey RandomEtc ... I'm not sure what you mean by setting up a proxy or why that is useful, I'm just getting a 404. I provided a sample 404 that is requested, but here it is again:

http://us.maps3.yimg.com/aerial.maps....

> if you can figure out what's wrong and provide a patch I'd be happy to apply it.

Sure, the root problem is that the xml request isn't blocking, so you might want to fix that. The workaround was this paint queue, I think, but it also got broken because the versions were set at construction:

protected static var __roadVersion:String = "w2.66";
protected static var __hybridVersion:String = "w2t.66";
protected static var __aerialVersion:String = "24";

So tile requests that aren't ready never get put onto the queue:

if (__roadVersion && __hybridVersion && __aerialVersion)
super.paint(sprite, coord);
else
enqueuePaintRequest(sprite, coord);

All you need to change is to create the version vars with null and then set them to defaults on the failed xml response handler.

EDIT: Is there a code mode for inserting code snippets?

Thanks, those values worked for me too ... but the AS3 code I have for AbstractGoogleMapProvider is a bit broken.

It doesn't appear that the XmlThrottledRequest is actually blocking like it is supposed to. So the first request for google tiles are failing since the defaults are stale.

I see there is a __paintQueue to probably mitigate this, but it isn't working right.

Anyone else confirm this as a bug? If so I can provide a solution.

EDIT: Also, it appears Yahoo! maps (hybrid) aren't loading right either. Anyone else confirm this? Here's a failed mm url:

http://us.maps3.yimg.com/aerial.maps....

A bump to this ... so is it a typo bug or not?

A bump to this as I'm experiencing the same issue ... although I'm sure it is easy to figure out. If I don't hear anything today I'll look into it tomorrow and post a solution if I come up with one.

Try turning off the well and the grid area from the TileGrid (in the core package). You'll want to set these to false:

protected var _drawWell:Boolean = false;
protected var _drawGridArea:Boolean = false;

These caused havoc when I was doing transparent and semi-transparent images. They don't seem to be of any benefit that I can tell.

Can't you just set the Map with a new map provider when you detect you're at a specific zoom level? Just set a zoom level hook onto the map and adjust as necessary.

Or am I missing something?

Hey Gill ... you'd just need to extend the AbstractImageBasedMapProvider.

Hey Opa-

That getTileUrl() is the only unique method and I pasted it above. The constructor just sets the transformation and domain. Check any of the other providers on how to do this, they are all exactly the same.

> 1-Set up Geoserver + TileCache to work with my dataSet

I followed the instructions on geoserver on how to add a shapefile ... it takes about 5 minutes. From there you can go to the demo sections and check out the sample map requests, you're going to want the WMS GetMap service. Sorry, I'm not using tilecache.

> 2-Set up ModestMap : Change the map provider

For this I took the AS3 flash example and added my own map provider. I was interested in a US basemap so I rendered my tiles transparent to see how they lined up to the other providers (yahoo!, ms, google). You'll just need to extend the image based map provider and set the same transformation as the other map providers (they are all the same)

> 3-Convert given coordinates to a web projection based bounding box.

This is the part that takes a little math. I'm going to put some code below and I don't think there is code support on this forum so it might get a little ugly.

Here's the interesting part of my WMS request:

private const wms:String = "wms?layers=namespace:name&srs=EPSG:900913&Format=image/png&request=GetMap&height=256&width=256&transparent=true&bbox=";

You'll need to put your own layer in there depending on what you set up in geoserver. At the end you'll noticed a dangling bbox ... that's what you have to compute given your coordinate. Here's what I did:

// radius of the earth in meters
private const Re:Number = 6378137.0;

public override function getTileUrl(coord:Coordinate): String {
var dist:Number = 2 * Math.PI * Re / Math.pow(2, coord.zoom);

var left:Number = (-1 * Math.PI * Re) + (dist * coord.column); // minlon
var right:Number = (-1 * Math.PI * Re) + (dist * (coord.column + 1)); // maxlon

// might need to scale by 85.0 / 90.0, not sure, I didn't have to
var bottom:Number = (Math.PI * Re) - (dist * (coord.row + 1)); // minlat
var top:Number = (Math.PI * Re) - (dist * (coord.row)); // maxlat

var bbox:String = "" + left + "," + bottom + "," + right + "," + top;

return wms + bbox;
}

That's it ... if you're not sure what is going on I'd be happy to explain.

Hey Gill ... I can help but I have a few different things I'm doing so I'd like to know what you're trying to do.

If you're using geoserver and tilecache then it seems all you're doing is extending the image based map provider and overriding getTileUrl(), right?

If that's the case you just need convert your given Coordinate to a web projection based (EPSG:900913) bounding box.

If that's what you need I'd be happy to share the math to do it.