[mkgmap-dev] Is dem-tdb branch ready for trunk ?

Sat Jan 27 09:49:55 GMT 2018

Hi

The idea of a dem.zip sounds would have some major disadvantages

1) Data can only be 3arc or 1 arc not both

2) 1 arc data to me is more preferable but contains void data which have 
to be replaced with 3arc data

Nick


On 27/01/2018 09:40, Thomas Morgenstern wrote:
> Maybee we can create a ready to use DEM-model, store it like the 
> bounds.zip and see.zip ? The user can download it and mkgmap reads the 
> DEM from downloaded #DEM.ZIP# ?
> This method would be a graet advantage for users, who not so familiar 
> with the DEM .
> Regards Thomas
> --------------------------------------------------
> Von: "Gerd Petermann" <GPetermann_muenchen at hotmail.com>
> Datum: Samstag, 27. Januar 2018 08:54
> An: <mkgmap-dev at lists.mkgmap.org.uk>
> Betreff: [mkgmap-dev] Is dem-tdb branch ready for trunk ?
>
>> Hi all,
>>
>> I am not aware of any erros in r4091, so I think it is time to merge 
>> it into trunk.
>>
>> I see only one problem: HGT data changes rarely, so I'd prefer to do 
>> the costly DEM calculations
>> only once and be able to store the results.
>> I've already described how to do this here [1] but I'd prefer to have 
>> a container format that allows
>> mkgmap to extract the Garmin DEM bitstream data for a given lat/lon 
>> pair from a file.
>> Such a container could contain the DEM data for one or more dem-dist 
>> values. It could be empty first
>> and grow each time you calculate DEM for a new area. In subsequent 
>> executions of mkgmap it would
>> check if the container already contains the data for the wanted area.
>> Advantage would be a faster tile compilation and less power 
>> consumption, disadvantage would be the
>> additional disk space and higher complexity.
>>
>> [1] 
>> http://gis.19327.n8.nabble.com/Performance-with-zipped-hgt-files-tp5909756p5909801.html
>>
>> Gerd
>>
>>
>>
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