Beginner's queries

[Anthony Appleyard]

I used Terragen a fair amount around year 2003, but since then Terragen has changed greatly.

Is Terragen Classic the version of Terragen as it was current around 2003? Is it the sort of Terragen that had Terragen world files -----.tgw ? Can it still be downloaded, and installed alongside the modern Terragen so I can run either as I want to?

I made the image displayed here. Various queries:-
0) I don't fancy scuba diving there while that dredger's in the lake.
1) How can I make color vary according to steepness of ground?, so that steep ground is browner or greyer.
2) How can I make color vary with altitude?
3) How can I make the land under the water another color? Land grass does not grow underwater.
4) If I import an object from an .OBJ file, and it is 1 .OBJ file unit long, and in Terragen I scale it 1.0, how long it is in Terragen by Terragen conventional length? The dredger is about 40 feet long if 1 .OBJ file unit is treated as about 100 inches, as in Poser.
5) In the 2003 Terragen I made a Terragen world "underwater.tgw" for scuba diving scenes by:
*-- Make the Terragen water opaque and sand-colored to represent seabed sand at the bottoms of the rocks.
*-- Dense green/blue haze.
*---- But: Is there a way to make the Terragen sky look like water surface overhead? Or how to make water surface overhead?
6) I found that if I set the wave height too high, the waves get unnaturally high. Could the water wave maths be set so that if waves get too high compared to wavelength, the tops break and make foam? (In the real world, wave speed of waves on water varies as square root of wavelength .)
7) If I make a model of a reed, can a population of them be distributed only in shallow water, not on land or in deep water?

[jdent02]

Most of the distribution questions (colors, textures and populations) can be controlled with either a painted shader (for manual control) or the slope/altitude tab on the distribution shader and surface shader.

[Dune]

First of all, TG3 is very different from the classic Terragen, and you can't import tgw's.
Second; TG3 is much more versatile, so 'forget' about the classic and dive into TG3.
Third; indeed, color and displacements can be controlled by the height and slope controls in surface shader and distribution shader, so there you go for a lot of your queries.
Then objects; it depends on how the objects were made, so you better check with the measure tool, or add a card (which is default 1x1m, but can be changed) to compare sizes. If an object is not on scale, use Poseray to change it.
There is a way to make water overhead by for instance adding another sphere with size and location of planet, but inversed size, turn shadows off, add a surface shader (no color) and use the displacement offset to raise the water level above ground. Add a water shader to that. Well, I made a you a very simple setup.
Objects can be distributed with a distribution shader (not attached to anything, but using the final position slope and altitude tabs)
Wavetops can be 'foamed' kind of, by using the height restriction in an extra added surface shader, below the water shader, or using favour rises.

[Anthony Appleyard]

Thanks for the underwater scene.

I did this earlier :: I made an .OBJ object which was a plain cube, 1 x 1 x 1 in .OBJ units. I imported it into a Terragen job, and moved it past a fixed point on the lines around the camera, and thus the cube proved to be 1 meter long that direction. So it seems that 1 .OBJ unit is 1 meter in Terragen and about 100 inches (2.54 meters) in Poser.

In linear plane waves of one wavelength in deep water, particles near the surface move not plainly up and down but in vertical circles, forwards above and backwards below. As a result, the surface of the water forms not an exact sine wave, but a curtate cycloid with the sharper curves upwards. As (wave height) / wavelength increases, the wave shape becomes more like a cycloid, and when (wave height) = wavelength / π, the wave shape becomes a cycloid, with the cusps upwards. If something such as wind tries to make the wave any higher at that wavelength, the wave shape tries to become a prolate cycloid, which has a loop at its cusps, and the wave's crest breaks up into a line of foam commonly called a "whitecap" or "white horse". Likewise, in a mixture of waves of various lengths moving in various directions and long waves overtaking short waves, as often seen at sea, if at any time and place the resulting wave motion "goes prolate" and tries to make water go in a raised loop through other water, it cannot, and some of that wave's energy is used up in throwing up spray and foam.

In water waves, speed varies as square root of wavelength. Wave speed on deep water in Earth gravity is about 1.25 x square root of wavelength, in seconds and meters.

[Anthony Appleyard]

Thanks for the underwater scene.

I did this earlier :: I made an .OBJ object which was a plain cube, 1 x 1 x 1  .OBJ units. I imported it into a Terragen job, and moved it past a fixed point on the lines around the camera, and thus the cube proved to be 1 meter long that direction. So it seems that 1 .OBJ unit is 1 meter in Terragen and about 100 inches (2.54 meters) in Poser.

In linear plane waves of one wavelength in deep water, particles near the surface move not plainly up and down but in vertical circles, forwards above and backwards below. As a result, the surface of the water forms not an exact sine wave, but a curtate cycloid with the sharper curves upwards. As (wave height) / wavelength increases, the wave shape becomes more like a cycloid, and when (wave height) = wavelength / pi, the wave shape becomes a cycloid, with the cusps upwards. If something such as wind tries to make the wave any higher at that wavelength, the wave shape tries to become a prolate cycloid, which has a loop at its cusps, and the wave's crest breaks up into a line of foam commonly called a "whitecap" or "white horse". Likewise, in a mixture of waves of various lengths moving in various directions and long waves overtaking short waves, as often seen at sea, if at any time and place the resulting wave motion "goes prolate" and tries to make water go in a raised loop through other water, it cannot, and some of that wave's energy is used up in throwing up spray and foam.

See http://mathworld.wolfram.com/CurtateCycloid.html and http://mathworld.wolfram.com/ProlateCycloid.html

In water waves, speed varies as square root of wavelength. Wave speed on deep water in Earth gravity is about 1.25 x square root of wavelength, in seconds and meters.

[Anthony Appleyard]

... There is a way to make water overhead by for instance adding another sphere with size and location of planet, but inversed size, turn shadows off, add a surface shader (no color) and use the displacement offset to raise the water level above ground. Add a water shader to that. Well, I made a you a very simple setup.

Thanks. I moved the camera up until it was above sea level and the sea depth seems to be 256 meters = about 840 feet.