[Loadstone] checkpoint distance

Shawn Kirkpatrick shawn at loadstone-gps.com
Thu Sep 16 02:22:10 BST 2010


You're probably not going to get that kind of pin-point accuracy for 
navigating around a building. The gps inaccuracy will really come in to 
play, possibly even effected by the building itself. You're better off 
breaking the route down in to simple steps rather than a lot of complex 
ones. Gps can get you to a building but you'll most likely need your 
orientation skills to find the door.

On Wed, 15 Sep 2010, Peter Wendorff wrote:

> Hi Shawn.
> Thanks for your answer. Let me explain shortly what I try to do:
> I want to provide "real" route descriptions for (blind) pedestrians.
> When I tried the first time my problem was, that there has been other 
> checkpoints nearer than the "neighbours" along route. For example when going 
> around a building - 100 meters north, 15 meters west, and then back south the 
> points near the start position has been anounced again - definitely the wrong 
> points.
> So I wanted to avoid that by providing more points in between. My 5 meter 
> distance was a first try to do that - and yes, thats too short, but 15 meters 
> are too high in much cases, I fear as long as it's not possible to give 
> arbitrary long instructions - lodestone is restricted to 75 characters; not 
> enough to desribe more than the next simple routing step.
>
> I know the restriction of about 1000 checkpoints - and that's not good for 
> practical purposes of longer routes with good descriptions, but for my tests 
> loadstone is working.
>
> On 15.09.2010 22:18, Shawn Kirkpatrick wrote:
>> Well, 5 meters is way too short for distance. Average gps accuracy is 
>> around 15 meters so you'd want distances higher than that. If you do what 
>> it sounds like you're doing, putting in all points as checkpoints, you'll 
>> have a lot of output and the program probably won't be useful for much 
>> else. You can only have about 1000 checkpoints before the program runs out 
>> of memory so trying to store everything as a checkpoint just won't work.
>> 
>> On Wed, 15 Sep 2010, Peter Wendorff wrote:
>> 
>>> Hi.
>>> I try to create checkpoint route files currently.
>>> My test file used distances between points of 5 meters and - my first test 
>>> file - distances as given by the openstreetmap data (nodes describing the 
>>> street- usually at least one node per direction change and intersection)
>>> 
>>> 5 meters I considered as too much nodes, the screenreader repeatingly 
>>> started reading "Ankunft " and part of the first name-sibling, but never 
>>> speaking the whole content, because the next point is announced before 
>>> (German "Ankunft" is arrival in English - not sure what's the word used in 
>>> English loadstone).
>>> 
>>> My question is: what's known as good smallest distance between points to 
>>> avoid that behaviour?
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>>> 
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>
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