KML Layer

[Tim G]

Ok, I've been having a little fun building a quick-and-dirty KML Layer. I've seen other mentions of this around here, I'm not sure if anyone else is doing the same thing. I thought I'd share a few screen caps and my experiences.

First is a KML file of the Appalachian Trail. The file has about 30 LineStrings with a total of a couple hundred thousand points. At first, I tried to render all the points, but it was too slow. So I've changed my code to simplify the LineString for the current view. With that, I get plenty of FPS and, if you zoom in, you still see all the detail you need.

Here's a cap of the whole trail:
http://homepage.mac.com/timgleason/.Pictures/AT1.png

And one of the end:
http://homepage.mac.com/timgleason/.Pictures/AT2.png

Next are some caps of a KML file with 3d models(*) of Vancouver's buildings. Some of the things in this file I don't render. Most I don't render correctly. Worse, I'm so far unable to optimize it enough that the framerate is even reasonable. The KML file is big, but I think I should be able to render faster -- I need to figure out how to cache the right data. Right now, with this model, I get about 2FPS (yikes). All the same, I think it looks promising.

Here's the whole city:
http://homepage.mac.com/timgleason/....Vancouver3.png

Here's a zoom in:
http://homepage.mac.com/timgleason/....Vancouver2.png

And this is from the coast:
http://homepage.mac.com/timgleason/....Vancouver1.png

The bad news is that I'm new to OpenGL, so a lot of what I've written probably sucks pretty bad. Once I get a little further along, I'll add some comments. I'll post the code if anyone is interested. Maybe someone can improve some of my rendering code.

--t

* The 3d Models in this file are not really models. They are just extruded polygons.

[shin103]

Tim,

Nice work, I am planning to work on kml next ... did you use the kml posting from Chris Maxwell's posting to read the kml?

Shin

[Tim G]

I wrote my own parser. It's pretty simple. Right now it only parses what I might want to draw.

I did some work this weekend and things are getting better. I implemented proper shading for the polygons -- they look pretty nice. And I improved the performance enough that you can scroll around that full city pretty quickly. I didn't measure the framerate, but it was pretty reasonable.

I also added a tree view so you can select an item from the file and pan to it.

I'll be away this week, but I think I'll post the code shortly after I get back in case anyone wants to play with it...

--t

[patmurris]

Nice work Tim! Any more progress on kml since then?

[Tim G]

Ok, looks like I had less time than I thought I might

Since I promised something, I have uploaded what I have. I does a subset of KML - polygons (extruded and with holes), lines (tessellated) and points as pushpins (right now it ignores point styles). It is reasonably performant -- but could always use work.

It has a simple example viewer that loads three sample KML files (that are zipped with it -- you must run from the unzip dir). The viewer includes a tree pane. You can double-click on a leaf node in the tree and the globe will pan zoom to that point (more or less, zoom is just a guess).

I put a readme file in there that gives a short overview of the code. I also put some comments in the main class (KMLLayer) that should help to understand it.

Try it out and let me know how it does. I really only tried to get it to work with a handful of test files. If you have a file that you want it to be able to display but it doesn't, post a link. If I have free time, I will try to make it go. (Ditto for files that display poorly or slowly).

The code with the samples is here: http://idisk.mac.com/timgleason-Public/kmllayer-0.1.zip

Let me know if you have any questions...

Thanks,
tim

[krheinwald]

That feature included in the next release would make a nice (early?) Christmas present .

Together with an example to start/feed the WWJ applet with an KML/KMZ file, I already know two sites where I would integrate the WWJ applet ASAP.

Klaus

[asantiago]

Hi, a bit later but I have some KML code.
It was created using KML2.2 and JAXB.
I haven't made depthly test but waht I'm tested works fine.

I have a couple of links in my blog and if any is interested I can publush the code without problems.

Bye.

[TomServo]

Think we have like 3 different attempts at KML so far.. be nice if we can merge them into 1 and get a complete KML support going so what you see in GE, is what you see in WWJava.

[wen.xiong]

Hi Tim G
I downloaded the kmllayer-0.1.zip ,and unzip it,but the folders images and models are null.
there is a line (import worldwind.kml.KML3dLayerin file SimpleClient.java ,i can't find the class worldwind.kml.KML3dLayer.
what happened?
thank you

[Tim G]

I'm not sure what you meant in the first part of your comment. But KML3dLayer was just an old version I deleted. Just delete the import line and you should be fine.

--t