[Loadstone] checkpoint distance

Peter Wendorff wendorff at uni-paderborn.de
Wed Sep 15 22:39:37 BST 2010


  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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