Hi,

I recently stumbled upon Keyhole and found it to be a great APRS mapping system. So I am a Keyhole newbie. Here's where I'm at with the APRS stuff so far (see my post in Overlays - User Favorite Custom Images too).

APRS Station Kml

Track a station the station may expire - try substituting another mobile callsign. Load this link along with the one above for maximum effect.

Here are my questions/suggestions. I did search for the answers, but didn't find anything conclusive. I apologize in advance if I'm bring up old questions that were already addressed:

1 - I see posts discussing different parts of the kml document but no comprehensive schema documentation. Does such a document exist? It would really reduce the amount of trial and error.

2 - How do I get my custom icon png's to have a transparent background in Keyhole like the built-in icons? Here's one of my icon maps as png24 used in examples above

3 - Is there a way to insert remote link folders into existing keyhole folders so new subfolders and placemarks can be added on the fly later? In other words, right now, if someone launches a remote kml link, it's placed relative to the root folder each time even if it has the same folder name as an exisitng folder. Can I make these links go under an existing folder name using kml somehow?

4 - Is there a way to draw a great circle path between two points using kml? LineString doesn't look like it follows a great circle. The line/path measurement tool makes such a line. It would be nice to do this from a kml document.

5 - The altitude value of "coordinates" doesn't seem to work for placemarks at least. It would be nice to place points and placemarks in space; e.g. plane, balloons, and satellites. Not sure what to do if it's underground though? Maybe the earth model should include the crust, mantle, and core This makes me wonder if Keyhole has a "universal" coordinate system that could allow for placement of planets in the solar systems, or even other stars systems and galaxies!?

6 - Option to have Keyhole follow a selected "moving placemark."

7 - Auto-update an object's description in the description fields after a remote link "refresh" if it is selected in the list or on the right mouse placemark menu.

8 - Does Keyhole support any xml data compression techniques to aid in the transmission of large kml files?

9 - Following the above logic, provide a means of connecting to other remote streams of data, e.g. a stream of dynamical placemarks like the APRS example. Google/Keyhole may not be too keen about this idea since it enters the realm of server system sales but could increase client sales dramatically.

That's it for now. Any suggestions, comments, or answers to the above are really appreciated. This is a very cool product

Regards,

Mike

What do you mean in #1?

And what version of Keyhole do you have?

To quote w3.org:

"XML Schemas provide a means for defining the structure, content and semantics of XML documents" like kml. For example, I didn't know a LineString tag existed until I saw a post here. What other content and capabilities are unknown to me (or others)? How do I properly use what little I do know? A Kml schema or spec would show all the tags and hopefully explain there use.

I'm using Keyhole 2 NV. I put some APRS stations on Mars see (bottom of page)

Mike

Mike,

This is a great set of questions. Several will be addressed in a future release.

1) no schema published at this time. It is available to NDA enterprise customers, but there are additions/changes coming soon that need to be made before it is published.

2) using 32bit PNGs with alpha transparency should get you what you want.

4) there is no circle primitive in KML, so linestrings are the way to go

9) if the data is formatted as KML, then network link does exactly what you want.

Thanks for the quick response. I was able to get the transparent png's to work. It looks a lot better now.

On the great circle, you are suggesting building myself a set of connected lines that follows the great circle route?

Finally, can you point me to examples of using network kml files to build a nest tree of folders containing network links from kml? I haven't been able to get this to work.

What I would like to do is have a folder under the root. In that folder will be a network link to a list of station placemards (just like the first link in my original post). All the mobile stations will have an html link in the description. If a user clicks on the link (selects a station from the list to track), I would like to add a network link that generates a placemark track (lineString) under the same folder in a TRACKS subfolder (like my second kml link in original post).

The desire is to build this tree structures in My Keyhole for other as they select the remote kml files. Here is a graphical example (I hope it makes sense):
Code:

---

- ROOT
     -REMOTE APRS
           -STATION LIST (remote link)
           -TRACKS (stations added on the fly by selecting a url for a station above)
                        -TRACK for station 1 (remote link station 1)
                          .
                          .
                        -TRACK for station n (remote link station n)  

---

Regards,

Mike

Yes, draw circles as linestrings (rendered algorthimically in lat/long space... not necessarily an easy proposition).

I think I understand what you want, but I don't think there's an easy way to get there. A possible solution would be to maintain per-user state-information on your server so that when a user downloads his current station list kml file, you know who he is and the URL that he clicks back to your server contains cookie/key information for you to edit, on the server, the entire heirarchy for that particular user. That's not easy, but KML doesn't offer a way to drop items into an existing heirarchy.

I would like to discuss the question that w7mjr asked in his original post. "6 - Option to have Keyhole follow a selected "moving placemark." I have tried to implement this using a network link. PenguinOpus said that if the data is formatted as KML, then a network link does exactly what you want. I assume that means modifying the coordinates in the point tag, and longitude and latiutude in the View tag. I must be doing something wrong. I have created a network link to a kml file that displays a placemark and sets the view tags to the same lat/lon. The placemark shows up at the correct location, but my view does not change. My refreshVisibility and visibility tags are all set to 1. What could I be doing wrong?

thanks,

Brendan

Brendan,

I'm sorry for the confusion. Networklink allows the update of kml data but does not provoke the fly-to that drag-n-drop or loading a kml file does. This means that there isn't a way to track a point without an external process constantly feeding new kml files (with a view) to the Keyhole program.

Thanks for the update.

Is there any work-arounds to this? We have built a client which sits between our data source and Keyhole. The client manages the data feeds, styles the XML from the web service into KML, and updates the source KML pointed to by the network link. Our demonstration is truely enhanced by the ability to fly via a new view tag. Any suggestions on how we can invoke flight without the user initiating it via the GUI? Can we programatically load/reload a KML file with just view info, but so it does not require the user to confirm the reload?

Any help would be appreciated.

thanks,

Brendan

Is your "Client" on the same computer as your Keyhole Client? If so, you can use the following technique. Have your program generate a KML file with the placemark, now invoke keyhole using the command line program >Keyhole filename.kml This works in any language that allows you to start a new program from within an existing program (I've done it with java and rexx).