[mkgmap-dev] Please help with news about new DEM options

Sat Feb 3 12:03:00 GMT 2018

Hi Gerd, 

I think that it is better to get a rational set of option names than worry
about causing confusion due to minor changes. I would think there are only a
handful of people using the DEM options at the moment, and I don't believe
anyone who is not on the development list will be using them yet. If there
is anyone who has picked up the options and is not on the development list,
they will get an error message saying they have an unrecognised option and
will very quickly sort out what has changed.

I think it needs to be explained that only one DEM overview is needed,
despite the fact that there may be multiple overview levels.

Arndt Röhrig suggested to me that the splitter output poly file be used when
I asked for a DEM Noddy Guide - if it makes more sense to use the one
provided as input to splitter then I suggest that be added to the
documentation instead, and possibly suggesting that the areas.poly from
splitter should not be used. I have been using areas.poly, but have not
tried with no --dem-poly option, so don't know whether it makes any
difference. Is this option intended to be used only when you want areas of
the map to not have DEM data? If that is the case, then the documentation
needs to say that in general this option need not be used (presumably using
the one provided as input to splitter will also have no effect in that
case). The wording of "If not given, the DEM data will cover the full tile
area" is not sufficiently clear to me.

Cheers,
Mike

Regards,
Mike
-----Original Message-----
From: Gerd Petermann [mailto:gpetermann_muenchen at hotmail.com] 
Sent: 03 February 2018 08:52
To: Development list for mkgmap <mkgmap-dev at lists.mkgmap.org.uk>
Subject: Re: [mkgmap-dev] Please help with news about new DEM options

Hi Mike,

- I  also wondered if mkgmap should produce more DEM levels when --dem-dists
is missing, the problem is that I was unsure about the values to use.
- I like your suggested option names but I'd prefer not to change the
options this late to avoid confusion.
- There is only one overview-dem-dist because MapSource and Basecamp don't
need more and the overview map is not used on the GPS.
- Can you explain what effect you expect when you use --dem-poly with the
areas.poly from splitter?
My understanding is that this should not change the map, at least not
visibly, as the areas.poly simply describes the outline
of the rectangular tiles. On the other hand it makes sense to use the poly
file that was used as input for splitter.

Gerd
________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Mike
Baggaley <mike at tvage.co.uk>
Gesendet: Samstag, 3. Februar 2018 09:29
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] Please help with news about new DEM options

Having read the explanation of --dem-dists I think that the default for when
the option is not provided needs to be changed. The explanation says "mkgmap
tries to determine a reasonable value based on the resolution found in the
*.hgt files", but it also says "for gps devices you need one for each
resolution given with the --levels option". It seems to me the default
behaviour should be to produce a map suitable for GPS devices, and hence it
should determine a set of values. I suggest renaming this option
--dem-distances as its meaning is clearer. Also I suggest capitalising GPS.

I suggest renaming --overview-dem-dist to --dem-overview-distance so that
all the DEM options begin with --dem. I also suggest moving the explanation
to immediately after --dem-dists. As --overview-levels allows multiple
values, does the DEM overview level also allow multiple levels (in which
case the name needs to be --dem-overview-distances)? If not, we need a
mention why only a single value is needed.

For the --dem-poly option, I suggest adding a mention that the areas.poly
file produced by splitter can be used.

Hope this helps,
Mike
-----Original Message-----
From: Carlos Dávila [mailto:cdavilam at orangecorreo.es]
Sent: 02 February 2018 21:33
To: mkgmap-dev at lists.mkgmap.org.uk
Subject: Re: [mkgmap-dev] Please help with news about new DEM options

El 30/01/18 a las 09:41, Gerd Petermann escribió:
> Hi all,
>
> with r4093 I've merged the dem-tdb branch into trunk. I think it would be
good to mention this in the
> "Latest news" on [1] , maybe with one or two screen shots, but I have no
idea how to write this "from a users view".
> Do we need a how-to that describes the sources for hgt files and maybe
more about the new options?
> It would be great if somebody could help with that.
>
> Gerd
>
> [1] http://www.mkgmap.org.uk/
>
>
>
Attached patch is not exactly what you asked for, but I hope it adds
some useful information about DEM.

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