[mkgmap-dev] [PATCH] Access destination tag

Sun Mar 1 19:42:49 GMT 2009


Mark Burton schrieb:
> Hi Robert,
>
>   
>> That's quite interesting! In my experiments, the access flags for  
>> "delivery" and "emergency" didn't behave like the other six, so if  
>> "delivery" is actually "destination", that'd be great.
>>     
I very well could imagine, this is the missing bit for 'destination'
>
> Yes, it would be great but do we actually know if the garmin is capable of
> avoiding routing into an area if the destination is not within that area?
>
> At this time, I can't picture how the gps could work it out. It would have
> to make nets of connected ways that all have that attribute to be able to
> route into that area - it seems to be (potentially) very complicated.
>
>   
I think the bit could mean 'dont use this street unless you must'. As 
the routing algortihm works from both sides, the following would be 
possible: If search is starting at such a road, it could take such roads 
as long it finds the first road without this flag. From there on it is 
not allowed to enter a road with delivery only. So there is no complex 
routing network.

The only case which must be excluded in this scenario would be an 'isle' 
of free roads inside other roads only usable for delivery.
>> For the record, calling these fields DELIVERY and EMERGENCY has to do  
>> with the cGPSmapper documentation: The RouteParams field ends in 8 bit  
>> flags which are named according to the vehicle types. We're assuming  
>> these 8 fields actually correspond to one byte in the IMG. This may be  
>> off, or the cGPSmapper may be inaccurate.
>>
>> But having flags "no delivery" or "no emergency vehicles" on a road  
>> doesn't make too much sense.
>>     
>
> No, but having a flag "delivery allowed" or "emergency allowed" does -
> imagine a pedestrian area that doesn't allow normal traffic but does
> allow delivery vehicles and could be used by emergency vehicles. Such
> areas exist, I have seen them.
>
>   
Would in this case 'delivery allowed' not mean the same as 
'destination'? In normal case you are not allowed to use the road by 
car. If you want to deliver something, then your destination is in this 
road (or area) and you are allowed to use it.