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#1 2018-05-24 11:16:14

Yves
Member
Registered: 2018-05-08
Posts: 1

Low definition's Problem with Openseamap's Opencpn Kap files (.7z)

Hello everyone,

I cannot figure out why the Kap files provided for download on openseamap have a very poor definition once loaded on opencpn, whereas the exact same area viewed online on map.openseamap.org are stunning of precision and quality... ?!

Is this an issue due to the compression ratio of the raster files ? vs. the vector ENC files used online ?
Any possibility to download the ENC files used on http://map.openseamap.org/ unstead of raster ?

Thanks for tip and advise

Yves
Brussel

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#2 2018-06-01 22:48:44

commodore.white
Member
Registered: 2018-05-31
Posts: 2

Re: Low definition's Problem with Openseamap's Opencpn Kap files (.7z)

It's not just Windows OpenCPN, the Android version is just as bad. I've been playing with AISpilot on my Android tablet of late. Its also uses OpenSeaMaps but it's like the difference between chalk and cheese. AISpilots rendering of OpenSeaMaps maps is gorgeous.

Annoyingly, North Sea Kap files are some 600Mb to download but get expanded to 1.5Gb before OpenCPN can make use of them. AISpilot seems to use the downloaded maps "as is"; important if you're limited on memory.

I'm going to try other Android apps that use Kap files and see if they render as badly.

Peter

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#3 2018-09-20 19:57:40

alta_schwede
Member
Registered: 2017-11-02
Posts: 8

Re: Low definition's Problem with Openseamap's Opencpn Kap files (.7z)

Hi Yves,

Yves wrote:

Hello everyone,
I cannot figure out why the Kap files provided for download on openseamap have a very poor definition once loaded on opencpn, whereas the exact same area viewed online on map.openseamap.org are stunning of precision and quality... ?!

Is this an issue due to the compression ratio of the raster files ? vs. the vector ENC files used online ?

the KAP files are based on the pictures (raster images, no vector data) that you can see in the online maps -  map.openseamap.org. Unfortunately, the KAP files support less colours than the online charts and a reduction of the used colors is required during the generation of the KAP Files. Another restriction of the KAP files is the "zoom" level or scaling factor. The online maps allows you to zoom until a level of eighteen, whereas the OpenSeaMap KAP file is using a maximum zoom level of sixteen.   

Yves wrote:

Any possibility to download the ENC files used on http://map.openseamap.org/ unstead of raster ?

Thanks for tip and advise

Yves
Brussel

I think this would be nice but it is not supported at the moment.

Tom

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