August 2003

from PaddyMcGee-TheUniversityOfAdelaide Website

 

 

 

 

This page displays some results obtained using POV-Ray to simulate the visual effects of terraforming on Mars and Venus. Elevation maps of these planets (obtained from the Web) were used as height-fields in POV-Ray. A "water plane" was then added to the POV-Ray scene, and its height varied in order to simulate different ocean levels.

This approach is purely pictorial, and makes no attempt to address the scientific or technological problems associated with actually getting such masses of water in place on these planets...

The following table of images shows the results in going from a dry planet to a nearly-oceanic planet. Within POV-Ray, the vertical scaling of both height-fields was the same, and the range of heights of the sea level was similar.

 

Note that some liberties have been taken with the image map used for Venus; it was generated from the elevation map that was used, with a bit of green thrown in for good measure.

 

 

Mars                                                                                                        Venus

 

 

It is to be noted that Mars has rather a southern-hemisphere bias on the distribution of land-masses, whilst Venus has a more even distribution for moderate ocean levels. However, Venus presents a more broken, island-based topography, compared with Mars' somewhat continental appearance.

In the last frame, Olympus Mons, Tharsis Montes, Alba Patera, Sinai Planum, Syria Planum and Solis Planum remain on Mars, and some of Valles Marineris is still visible. On Venus, Ishtar Terra in the north, and Ovda Regio, Thetis Regio and Alta Regio remain near the equator; Beta Regio is to the west at low-northern latitudes.

One of the above images may be wrapped around a sphere to show the three-dimensional appearance of the planet with the given water level.

 

This is shown below, for each planet, with three different longitudes and with a simple simulated atmosphere.

 

 

 

 

Venus
 

Three views from above the equator.

 

 

Left image: Aphrodite Terra lies roughly along the equator,

with Thetis Regio (left) and Alta Regio (right) shown as green.

The channels of Diana Chasma, Dali Chasma and Artemis Chasma are evident.

Meridian approx. 165º.

Middle image: shows Ishtar Terra near the north pole,

with Maxwell Montes as a small, dark green patch.

Eistla Regio lies south of Ishtar Terra, with Alpha Regio

and Lada Terra being the main land masses in the south.

Meridian approx.10º.

Right image: shows Beta Regio (green) in the mid-north latitudes,

with Devana Chasma running south from it.

Phoebe Regio and Themis Regio are equatorial and south, respectively.

Meridian approx. 290º.


 

 

 

 

Mars
 

View as per Venus images. For these images, the image map which provides the color information has been combined with the height-field image. Therefore, the different shades of blue in the oceans, etc., give an indication of the depth of the water.

 

This process also slightly modified the colors of the image map- just a hint of green.

 

 

Left image: Olympus Mons to the left (west), the Tharsis Ridge with Arsia Mons, Pavonis Mons

and Ascraeus Mons slightly to its east, and Valles Marineris just south of the equator.

The lake formed from Argyre Planitia is near the south-eastern limb. Meridian approx. 90º.

Middle image: Syrtis Major is just east of the meridian.

The inland sea formed from Hellas Planitia is to the south. Meridian approx. 315º.

Right image: Elysium Mons forms an island in the encircling northern ocean.

Meridian approx. 200º.



 

 


 Refinements to the planetary images

Extra elements may be added into the POV-Ray scene to produce a more elaborate and more realistic atmosphere.

 

The following four images were generated using a POV-Ray scene file based on one developed by Constantine Thomas. The extra goodies are specular reflection from water surfaces and variable-transparency clouds based on a cloud map of the Earth.

 

I have changed the atmospheric haze code slightly, and added some small-scale variation to the cloud bump-map, and used land- and sea-maps based on the image map used for the previous three views- alas, this means that the specular reflection layer does not work on the first four images shown below...

 

 

Mars 1

view from south of the equator.

The south pole is under the extensive cloud cover at the bottom of the planet;

Valles Marineris is just above the centre of the disc.
 

 


Mars 2

view from well north of the equator, after the northern mid-winter.

An ice cap has developed over the north pole, and Elysium Mons is visible just below the centre of the disc.

The northern limits of Hesperia Planum appear near the lower limb of the planet.

 

 

Venus 1

from above the equator. Aphrodite Terra is visible.
 

 


Venus 2

a crescent view.


 

Whilst these views are not unappealing, they can be improved.

 

Higher-resolution bump, image and cloud maps may be used, and specular reflection from water may be added. It is possible to wrap a height field (employing the same image as used for a bump map) around a sphere (using Gilles Tran's method for doing so in POV-Ray 3.5) and to project the planetary image map onto that, and to combine the resulting surface with an "ocean" sphere having specular reflection properties.

 

The ocean sphere can have an image map made from tinting the height field image with an ocean colour, in order to represent different depths of water. Media code can then be added to simulate the atmosphere, and a cloud map to give cloud cover.

This will then give a truly three-dimensional planet surface, with reflective water. An alternative is to use an image map, a land-area-only bump map, a specular mask to delineate water/land areas, a cloud map and atmosphere code, using multiple image-mapped spheres with specific transparencies to render the planet. It may be a minor point, but the bump map will give only the appearance of elevation- the planet surface will still actually be a perfectly smooth sphere.

Below are shown various views rendered using Gilles Tran's code, modified for this particular context.

 

Medium- to high-resolution maps have been used, from various sites, including NASA's Blue Marble site, and from www.space-graphics.com.

 

 

Mars

essentially the same views as on the first terraforming page.

No cloud layer, but specular water reflections, atmospheric haze,

and a "translucent" water layer to reveal depth variations.
 

 

 


Venus

As before. The land image map is, I think,

actually based on Magellan radar reflectivity data,

so it does not actually represent the true pigmentation

of the surface - whatever that may turn out to be...

 



Views of Mars (left) and Venus (right)

 including cloud maps.

On Mars, Valles Marineris is just above and right of centre;

the view is from south of the equator.

The image map for Mars has been modified as follows:

the height-field image was inverted (i.e. made negative) tinted with green,

and then merged with the "standard" image map.

This gives low-lying areas a hint of green...

In the crescent view of Venus,

reflection of sunlight is seen from lakes

in the Artemis Chasma region of Aphrodite Terra.

 


The cloud maps used are ones derived from images from Earth-orbiting satellites.

 

That is, the distribution of the clouds is relevant to the topography and atmospheric dynamics of Earth- not of Mars or Venus. Applying these cloud maps to Mars and Venus, as it were, is an approximation.

 

One might edit the cloud maps in order to reflect, to some degree, the topography of a wet Mars or Venus, but the possible atmospheric circulation patterns that would apply in each case are another matter again.
 

 

 


Mars poster
The below image is a mosaic image of various prominent or interesting features on Mars.