embedding gmap4

[kepPNW]

You might try looking at your file with Gmap4 displaying the Google aerial since you can zoom in a lot more than when looking at the topos.

With the aerial view displayed, zoom in all the way on any 'spike'.
Each noticeable bend in your track is a trackpoint your GPS recorded.

I think we can conclude that when zoomed in a bunch the Google map API does a more-or-less decent job of showing the data in your file on the screen, including the 'spike' data. But when not zoomed in a bunch, sometimes 'spike' data in a file is not shown correctly on the screen.

I'm curious if you zoom way in with Google Earth do the spikes look the same as with Gmap4?

It seems I'm having an incredibly difficult time communicating, here.

I'm definitely not pointing fingers at you, Gmap4, or anything else! Just trying to share info I thought you'd find interesting.

As I said, I'm extremely familiar with the data. I've only viewed it in Google Earth, Garmin BaseCamp, TopoFusion, and a few other apps, but not Google Maps until now. I carried the devices that recorded it step by step. I've edited it, at the point level, to clean up odd reflections off canyon walls and such.

I've also been a Windows developer since 1990, and other platforms before that. I know the Windows GDI, and how those spikes occur in certain circumstances. It's a function of mitering sharp angles between line segments, when the line thickness is greater than the distance between sequential points. Most apps overcame this years ago, so I was taken a bit by surprise to see it in GM now.

No spikes in Google Earth (or other non-Google apps). It has a far better algorithm, apparently, for line rendering. I think I could pretty well eliminate them in GM if I were to recode the KML to use minimal line thickness. Haven't bothered trying that, yet. Zooming deeply in with GM does eliminate most of the spikes, to the extent that the linewidth becomes fewer pixels than the distance between points, yeah.

Ah well, I think I've hit that point of TMI? You offer a very cool tool, and I'm sorry I dragged this off into esoterica.

[Joseph Elfelt]

Karl, thanks for the kind words about the software. I have certainly enjoyed developing it. The next update to the production code should get posted this month. Also, I am always happy to learn more and the topic of online maps is certainly rife with arcane stuff.

As another technical guy, I expect you share my interest in knowing exactly what is going on.
Edit: And if I have completely missed your point, I apologize.

With that in mind, I downloaded your KMZ file, de-compressed it and then copied the coords for part of the Table Mtn track. I then made a small kml file with those coords in a <LineString> with a width of 1 pixel. I hosted that file on Google Sites and below is a zoomed in view of part of the data I copied. I suspect you took a break here and while you were not moving your GPS continued to record a bunch of points which appear as spikes when you zoom the map out a bit.

I also looked at this small KML file by zooming in with Google Earth. GE shows the same collection of 'spike' data that is shown with Gmap4. You do have to zoom in a bunch to see it.

Unless I am completely missing something (always possible!), if other software fails to show the same 'spikes' in your tracks, then that software is filtering your data.

[kepPNW]

Ahhhh, I see where we're whooshing right past one another, now!

Yes, the rat's nest you found on top of Table Mountain is what Garmin GPS's seem to do when you stand still. Drives me nuts! You're right, in that you really only see this when you zoom way in. We stood in that spot for 15 minutes or so, pondering what to do next and just enjoying the summit.

I was talking about a different level of spiky-ness, though. One you really only see when zoomed way out. And it's not really in the data, but an artifact of rendering the data in particular ways. If you look back at that image I attached a few posts ago, especially around Warren Lake, you'll see spikes protruding at different places and in different angles at different zoom levels.

[Joseph Elfelt]

Whoosing indeed.
Sorry for being so dense and thanks for clarifying.
Yes, I see what you mean.

I studied the Mt. Defiance track near Warren Lake and compared Google Earth and Gmap4.
I think I see what's going on.
There are a few spikes in that area.
When you look at that area with Gmap4 and a zoom level of around 13 or 14 (rightclick to see zoom level) then the height of the spikes is exaggerated a bunch. Very odd and certainly not an accurate representation of the data in your file.

[kepPNW]

Yep, them's the ones. And the same KML doesn't do that in Google Earth. Different rendering engines; that's gotta be it. Glad we're in sync again!

[raven]

Joseph, do you mean by the "height of the spikes" vertical excursions in altitude in the GPS recorded data?

[zee]

[zee]

https://maps.google.com/maps?q=http:%2F ... 8&t=h&z=20

the lat/lon of the center of all the gifs is identical.

[Joseph Elfelt]

Yep, them's the ones. And the same KML doesn't do that in Google Earth. Different rendering engines; that's gotta be it. Glad we're in sync again!

The funny part is that Google is telling us API developers that they want stuff to look the same in both GE and API apps. I am going to file a bug report with Google on this. We will see what response I get - if any.

[Joseph Elfelt]

Joseph, do you mean by the "height of the spikes" vertical excursions in altitude in the GPS recorded data?

No. I used a poor choice of words.

By 'height' I meant the perpendicular horizontal distance from the track at that location.