Author Topic: Heightmaps with bathymetry data  (Read 7165 times)

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Offline uci

Heightmaps with bathymetry data
« on: May 05, 2011, 06:26:43 PM »
Name: Europe
Data: ETOPO1 1-arcmin
Projection: Lambert Conformal Conic, SP:40N/56N, CM:10
Height resolution: 400 m
Surface resolution: 4 km x 4 km
Depth water cut: -4000 m
Map size: 898 x 1081
nr. levels: 20

water level: 0

winter snowline: 1
desert climate: 0
tropical climate: 0
mediterranean climate: 0
temperate climate: 3
tundra climate: 5
alpine climate: 7

http://simutrans-germany.com/files/upload/europe.zip

Name: Japan
Data: ETOPO1 1-arcmin
Projection: Lambert Conformal Conic, SP:23N/45N, CM:136
Height resolution: 500 m
Surface resolution: 2 km x 2 km
Depth water cut: -5000 m
Map size: 783 x 1055
nr. levels: 17

water level: 0

winter snowline: 1
desert climate: 0
tropical climate: 0
mediterranean climate: 0
temperate climate: 4
tundra climate: 5
alpine climate: 6

http://simutrans-germany.com/files/upload/japan.zip

Previews bellow.
« Last Edit: May 09, 2011, 10:49:08 PM by IgorEliezer »

Offline An_dz

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Re: Heightmaps with bathymetry data
« Reply #1 on: May 05, 2011, 07:24:41 PM »
Wow great, May I ask how you did it?
So perfect.

This sure must be on maps.simutrans

Offline vilvoh

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Re: Heightmaps with bathymetry data
« Reply #2 on: May 06, 2011, 07:47:41 AM »
Really impressive work! seems very smooth.

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Offline uci

Re: Heightmaps with bathymetry data
« Reply #3 on: May 08, 2011, 01:25:10 PM »
Wow great, May I ask how you did it?
So perfect.

This sure must be on maps.simutrans

The process is straightforward and does not require image editing. Following resources are needed (all free):

Source data: Etopo1
GIS software: VTBuilder (part of VTP package)

More maps might come, but I would like to see first if there are some suggestions for improvements.

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Re: Heightmaps with bathymetry data
« Reply #4 on: May 08, 2011, 01:37:50 PM »
Just returned from a holiday...

Looking good, will look at it in detail later. Always interested in new maps!

Is there any other source reference than "uci" needed?
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Offline An_dz

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Re: Heightmaps with bathymetry data
« Reply #5 on: May 08, 2011, 05:19:07 PM »
The process is straightforward and does not require image editing. Following resources are needed (all free):

Source data: Etopo1
GIS software: VTBuilder (part of VTP package)

More maps might come, but I would like to see first if there are some suggestions for improvements.

Thanks for sharing, I'll give it a try.

Offline uci

Re: Heightmaps with bathymetry data
« Reply #6 on: May 09, 2011, 12:14:35 PM »
Is there any other source reference than "uci" needed?
Another source of bathymetric data with global coverage is GEBCO. It is an alternative to ETOPO1, with greater accuracy, but more noisy. Since Simutrans is not a marine simulator, any of these sources offer more than enough accuracy.
 
For comparison see images attached and download below.

Name: Strait of Gibraltar
Data: ETOPO1 1-arcmin / GEBCO 30-arcseconds
Projection: UTM, Zone 30
Height resolution: 200 m
Surface resolution: 1km x 1km
Depth water cut: none
Map size: 202 x 263
nr. levels: 16 / 17

water level: -2

http://simutrans-germany.com/files/upload/gibraltar.zip

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Re: Heightmaps with bathymetry data
« Reply #7 on: May 16, 2011, 03:26:32 PM »
All maps have been added to the Simutrans Maps website.

Although the maps are very good, I have one point of criticism. We Dutchmen in the Netherlands don´t live underwater. The fact that half of our country is below sealevel does not mean we need divers equipment to live in our houses, nor that we have underwater trains.  :)

That is of course always the trouble with automated data, or better, the automatic interpretation of automated data.

Still, thank you for your contribution, uci, and I hope you will make more maps. (Hint: especially the African continent is lacking good maps...).

By the way, the Strait of Gibraltar maps were added in the World section as the map stretches over more than one continent.
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Offline uci

Re: Heightmaps with bathymetry data
« Reply #8 on: May 18, 2011, 10:52:34 AM »
... I have one point of criticism. We Dutchmen in the Netherlands don´t live underwater. The fact that half of our country is below sealevel does not mean we need divers equipment to live in our houses, nor that we have underwater trains.  :)
Thank you for this critical observation.

It will always be a problem with such low lands, like a river delta. There is no fault in the data, just our interpretation of the data. We may think to shift upwards the elevation a little, but problems will appear in other places along coastlines.

In spite of this, there is a way to recover dry land below sea level. I will summarize the steps below to see if it worth the effort.


In this figure the land below sea level is coloured in blue. We also have the coastlines superimposed over the map. Theoretically, anything inside coastlines is dry land or some sort of rivers/lakes. Indeed, the Netherlands is placed in such a location.


Topographic data, like SRTM 90m or GETOPO30, contain data only inside these coastlines. Over open oceans they have no data. This can be used to create a land mask map, for example using GETOPO30 data.


At this stage we require an image editor to combine the land mask map with the map produced from bathymetric data. The final result is shown here as a Simutrans map.

Using this technique I create a new version of Europe map below. Please compare it with the original one. Comments are welcomed.

http://simutrans-germany.com/files/upload/europe2.zip

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Re: Heightmaps with bathymetry data
« Reply #9 on: May 19, 2011, 06:50:40 PM »
Better. Much better! I can feel dry ground below my feet now!

That seems to be a good technique you are describing. The Wash area in England, the Venice area in Italy, West Denmark and the Baltic coast are looking much better now. It also seems to be a lot of work to do this.

I don't know if I'm asking too much of you, but in the last map I am missing the edges of Europe: Iceland, Southern Spain, Portugal, Southern Italy, North Scandinativa etc. etc. Could you perhaps make a new map with the whole of Europe on it?

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Offline uci

Re: Heightmaps with bathymetry data
« Reply #10 on: May 20, 2011, 04:35:18 AM »
Did you try the map from the archive attached?

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Re: Heightmaps with bathymetry data
« Reply #11 on: May 20, 2011, 08:01:39 AM »
Oops, obviously not  :-[ .

Thanks, it's an awesome map. I've updated it on Simutrans Maps.
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