Friday, August 22, 2008

On my next steps

My current goal is to finish a first version of the application ASAP. It will have only a minimal set of features, but it shall work and be available to everyone.

For the next improvement I have two options: either to start with drawing of the current track graphically or to implement smoothing. This update, for sure, will not yet show a graphical map: my goal is to have map rendering locally on the device, and making it a good quality is a very complex task, not for a fast update. For the first step I'm targeting to something similar to what GPS Kit does (only track, without map), but cooler :) It should already use OpenGL, support zooming, flying around, etc.

The second alternative is to implement smoothing, and I'm actually tending more to this option: the graphical presentation of a track is more an eye candy, while eliminating a manual pathway creation is a real improvement.

9 comments:

Michael said...

I think I previously posted that I'd like the eye candy :) so the user can see what is unmapped.

The smoothing sounds great if it can actually deliver a GPS Track that is good enough to convert almost directly to OSM ways. Do you think it could be that good? What about areas where the iPhone's GPS is scratching to get a lock? I get much better accuracy on my garmin than the iPhone in valleys with tree cover...

Michael

Michael said...

Oh, yea. Another question:

What happens if the app cannot access OSM at the end of the trail. Will it save the gpx for loading up later?

Michael

dtbow said...

Well, this is my big hope that the accuracy would be that good :) At least what I see currently from the GPS (17m horizontal accuracy) and read about combining GPS with accelerometer data (they speak about accuracy below 1 m) gives me a hope. GPS updates are coming every 1-2 seconds, so the timing should be ok.

Since OSM is working with straight line segments, to create OSM ways directly the application can try to draw a straight line that lies strictly inside all the (improved) accuracy neighborhoods where probabilities are higher than a certain threshold. As soon as the threshold is overcame, a new line segment is to be started. Similar techniques are used in pattern recognition and in robotics for map creation.

dtbow said...

To see what is unmapped, of cause, would be great. However, it would require a complete map rendering, not just a track shape view. Good quality map rendering requires time. I actually prefer to publish updates more often, for you to not forget about me :)

dtbow said...

The current version saves GPS data immediately to a file. In fact, you can close the application in the middle of the track (e.g. to drink a coffee or make a call) and then go back and continue logging. However, currently there is only one single log file, no UI is available to browse through files and select one to upload. I could (and probably will) change this in a future to support multiple log files, but not in the first version.

Michael said...

Sounds good.

I'd offer to beta test, but it doesn't sound like you can do any of that until you actually release through the App Store? How does that work - it sounds crazy to be so restricted for testing?

Does that mean a lot of the apps in the app store haven't had a whole lot of testing?

Michael

dtbow said...

Well, I must say, the whole development environment including various cryptography stuff looks very professional, much better thought through than by other platforms. However, you are right, it seems the designers of the system have forgotten about beta-testing. There is one way to install the application without publishing it to the App Store on up to 100 iPhones using special signature, but it is so screw up legally that I would do it only in case if I knew the people personally (or even better have a kind of signed contract with them - I think this was the Apple's idea).

For the apps in the App Store, if you ask me, it seems that some of them haven't been tested at all. Some of the errors they have are trivially to find even in the simulator.

Michael said...

So,

Any progress?

Hows it all coming along?

Michael

dtbow said...

Well, technically the progress is ok, but for a payed application to be sold over App Store one have to have an US tax payer id (even non US residents). I'm in process of getting one now.