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Map design for deep sea research

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#1
Nico Augustin

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    Ship and AUV/ROV based Bathymetry and Mapping
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After I introduced myself shortly I like to show here a bathymetric map that I made from the axis of the southern Mid-Atlantic Ridge at 5°S after the most recent workflow I use. The map mainly shows the graben in the rift axis with a so-called axial dome in the middle. This is basically a large active volcano with relatively smooth surface (due to large lava sheet flows). The axial dome shown in the map hosts at least three hydrothermal fields with venting temperatures up to >400°C (the so-called Turtle Pits, Comfortless Cove and Red Lion fields). I did not included any text in the map yet because I first like to show the bathymetry and explain what I did so far:

 

1. Fledermaus Pro 7.4:

Create a 40m cell size grid and export as ArcView asc-file

 

2. TTS 1.3:

Import asc-grid and render with 'Elevation - Texture' at 80, 'Vertical enhancement' at 4.5, 'Custom Palette', 'Color distribution' at equal-relative

 

3. Global Mapper 15.1:

Layer 1: asc Grid - Daylight shader (color white, translucency 40%)

Layer 2: asc grid Slope shader (max slope 40°, translucency 65%, hillshading disabled, blend mode: multiply)

Layer 3: TTS GeoTiff (Transparency set on black, 100% opaque, blend mode: multiply, Texture map: enabled)

export as GeoTIFF with background (void) pixels transparent

 

4. Photoshop CS6 (with Geographic Imager PlugIn):

simple correction on "Levels" and some subtile tuning with "Highlights/Shadows" and "Lightness/Contrast" to make the colors a bit more vital again and get rid of too dark shadows. 

 

5. Surfer 12:

Final map design (so far). Since TTS don´t exports a color bar I made one afterwards in Surfer (by having a grid file invisible laying as 'image map' in the background). The scale is made manually because Surfer can´t create a metric scale if I use degrees as unit (at least I did not find out yet).

 

I´m curious about your opinions so far and what may is good or not so good :-)

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#2
Hans van der Maarel

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Looks very nice. I get the impression the underlying terrain image is a bit 'soft', probably due to the resolution (the 40m cell size). What sometimes works is to do steps 1-3 at the data's original resolution and then in Photoshop increase the resolution in little steps rather than one big one. It's a bit more involved but yields better results.

 

 

 

The scale is made manually because Surfer can´t create a metric scale if I use degrees as unit (at least I did not find out yet).

 

That's because the length of a degree depends on your position on earth and the direction you're measuring in. The area you're mapping is relatively small and close to the equator, so those differences aren't too big and you can probably get away with using a scale bar (although technically that also depends on the map projection)


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#3
Nico Augustin

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Thanks - yes, the terrain is a bit soft because the native resolution of the data is about 40m only. The dataset is a bit older already and the weather conditions were not the best. So, usually we would aim for a resolution of 25 to 30m at 3000m water depth but thats only the theory. So. if we map larger areas the image often becomes a bit more crisp and less soft looking but we often also fight with artifacts.

 

Recently I work on maps of the Red Sea Rift which are getting much better. The resolution of the data is about 30m and better. The maps I may can post here soon too :-)






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