After a brief chat over at the MERP forums and here, it seems that L3dt is quite a good heightmap maker, however having no idea whatsoever and by trial and error not getting very far I created this thread to ask for a bit of help and to hopefully provide a basic guide for others before a full tutorial is made.

Anway, over to the main question, what is L3dt?

Its a 3d terrain generator that seems quite powerful. There is a free version and it can be obtained here:
http://www.bundysoft.com/L3DT/

All it takes now is to work out how to use it.

I already made a start on a tutorial, I'll post it here and update it:

What is a heightmap?


When you want to create a new worldspace in Skyrim, the first thing you'll need is a heightmap. A heightmap is a map that only determines the altitude of terrain. A heightmap does not contain any objects like trees or buildings, nor any textures.

In Skyrim, a heightmap is basically merely a grayscale image, where the whiteness of a pixel determines the altitude of that point. A completely black pixel means that the terrain is at the lowest point possible, a completely white pixel that the terrain is at the highest point possible. Heightmaps are often stored in a 16-bit RAW image format, which has 65536 different levels of brightness, and thus that many levels of altitude. The JPEG format for example, only has 256 levels of brightness.

A large heightmap is divided in several quads. A quad is a square image of 1024x1024 pixels. The entire Oblivion heightmap consists of about 18 quads in total. The quad shown beneath is from around Anvil, you can clearly see the sea and bay, which are the darkest parts:
http://img28.imageshack.us/img28/5470/anvil.png

In the game, the distance between two "pixels" on the heightmap is about 1.83 meters (1.8288221359252928, to be exact). Since a quad is an image of 1024x1024 pixels, the ingame size of a quad is about 1872.7 x 1872.7 kilometers:

http://cs.elderscrolls.com/constwiki/images/thumb/6/6b/ScaleGridQuad.jpg/600px-ScaleGridQuad.jpg





How do you make a heightmap?
There are two editions of L3DT, the Standard edition and the Pro edition. The Standard edition is free, the Pro edition is not, but it has a full trial of three months. The main limitation of the Standard edition is that the maximum map size is 2x2 quads, whereas the Pro edition allows up to 128x128 quad maps. Three months is more than enough to finish a heightmap, so I suggest to http://www.bundysoft.com/L3DT/downloads/pro-trial.php. The trials are handed out manually so it may take a day or two before you get it. You can just download the http://www.bundysoft.com/L3DT/downloads/standard.php edition for now, so you can continue with this tutorial and get some experience.

There are two "modes" in L3DT in which we will work, the Design mode and the 3D mode. In Design mode, you can make a rough general 2D map design of your heightmap by painting altitude and applying all kinds of terrain effects, like erosion. You can then let L3DT generate the actual heightmap based on those settings. After generating is done, you can go into 3D mode to get a 3D representation of the resulting heightmap, which you can then manipulate in any way you see fit to get everything exactly how you want.

Install L3DT in preparation for the next part.


Your first heightmap
To get a better picture of what I just said, I strongly recommend you to http://www.bundysoft.com/wiki/doku.php?id=tutorials:l3dt:fjord. You can skip the last parts, about Water Mapping and making the Attribute/Texture map. Those features are irrelevant to us, as the heightmap in TES games is only about altitude.

Once you are done with that tutorial, go back to the Design map of your Fjord, and in the menu at the top of the screen, go to "Operations" -> "Design Map" -> "Resize Design Map". In the first screen, just click "Next". In the second screen, set the HF/DM ratio to 16 and press OK. Note what happens, the pixels on the Design map have become a lot smaller. This means you have more control in detail, but allows L3DT less flexibility to generate the heightmap in a realistic way (which has become your responsibility for a greater part).

Experiment with the settings you learnt thus far. Make a new blank Design map and try something different than a Fjord. Experiment with the terrain effects of the Design map (Fractal Rough, Peak Rough, Terraces, Erosion) on Altitude differences, and change your HF/DM ratio a few times to get a feel for the consequences when generating the Heightmap. Getting a feel for this is important, as you get a general idea of which settings are necessary for different types of environments.


Getting serious
Let's start with the first version of the map that you actually want to make.


Editing or adding to an existing heightmap
If you already have a part of the map, for example if you want to extend the Tamriel worldspace in Skyrim and thus already have all of Skyrim which needs to stay intact, then the Design mode is useless. You will have to do it all in 3D mode.
You first need to get your hands on the RAW file of the Tamriel worldspace, once the CK is released you can probably get it by exporting it from the CK heightmap editor, or you can use a hopefully new version of TESAnnwyn to extract it. If you export it from the CK, it will probably have a separate RAW image file for every quad, so you'll have to piece those together in a RAW-compatible image editor, like Photoshop. Afterwards, in L3DT go to "File" -> "Import" -> "Heightfield", select the exported RAW file, in the next screen where it asks for horizontal scale fill in:

1.8288221359252928

Wait for the file to load, then go to 3D mode to edit your map.


Creating a new map from scratch
Go to "File" -> "New Project", select "Blank Designable Map", then go the next screen. Here you need to decide how big your map is going to be. First fill in the correct horizontal scale, which is:

1.8288221359252928

Unless you're going to make a map of 1 quad or smaller, tick the "Split map into tiles (mosaic map)" box, and select 1024 as your tile size (which is the size of one quad).

Now you should decide how big your map is going to be by filling in the Width and Height fields or using the sliders. The actual ingame worldsize will be displayed at the bottom of the current window. I can't help you pick a size here as it depends on what kind of map you want, but I estimate that Skyrim is not too far off from 4096x3072, a 4x3 quad map. At this time of writing the CK isn't out yet and I can't be bothered to check it out ingame, so feel free to correct me on this.

In the next window you pick your HF/DM (HeightField/DesignMap) ratio, which is the ratio of X heightfield pixels to one design map pixel. I recommend to go with 64 to start with. Press OK and there is your blank design map!

If you have a picture of the map you want to make, you can load set it as a draqe image for your Design map, which is great if you want to make an accurate map. First make sure the picture you're going to use as a draqe has the same aspect ratio of your design map (if your design map is a square, make sure your draqe image is a square as well) to avoid stretching. Then go to "View" -> "Image Draqe...", tick the "Load from file" box, and browse to where you have your map image saved. Press OK, and your map image will appear as a draqe on top of the green design map. You can adjust the transparency of the draqe by going back to where you selected file.

Now we're ready to start designing your map! I recommend to start with very rough layout first, which is best done at a high HF/DM ratio, like 64. Select Altitude, set it to 10, and press Apply to All, to make sure all the land is 10 meters above sea levels. Now set it at -10 and start painting the sea. Yes, the pixels are too big to accurately draw a shoreline, but don't worry about this huge inaccuracy at this moment, you'll fix it later.

After that I recommend to paint the altitudes of the flat areas of your map, to make sure the streaming rivers that go from inland to the sea actually go downwards (if that should be the case on your map). Start with an altitude of 15, find a river that ends in the sea, and paint the first two pixels following the river inland at an altitude of 15. Then set altitude to 20, and go further inland, following the river. Do this for all rivers that are supposed to go downwards in altitude, and after that fill in dry land parts between the rivers, so that overall the land goes slightly upwards as it you go further inland, where the mountains are. Whenever you encounter mountain areas, just leave them flat for now and match their altitude to the surrounding flat lands.

As a test, go to "Operations" -> "Heightfield" -> "Generate Map". This shouldn't take long, as there are no effects applied yet. The result will probably look really bad (especially the shore), but that's fine. The important thing is that the overall elevation for all the flat lands are correct.

Now you can start making the mountains. Go back to your Design map, select the Altitude brush, take a value between 10-20, tick the Relative box and take a Brush size of 1. With this brush you're going to paint your mountains altitudes. It may seem a lot easier to just take a large brush, set it at 300 and then paint it huge like that on the design map, but if you try that you will find that it results in very silly blocky mountains. By taking the smallest brush size and a low Relative value, you will automatically paint realistic height variations.
On the design map, hold your left mouse button and move it around chaotically where you want to pain your mountains. Logically, make sure you paint the most elevation at the centre of the mountains.

Whenever you feel like it, generate the heightfield again to see the results. The mountains will appear smooth and hilly, that's because no effects are applied yet. When you feel like you're ready, go to Design map and start using the effects. On mountains, especially use Fractal, Peak (peak doesn't make mountains pointy, it just causes greater height variations) and Erosion a lot, on hills especially use Fractal and Peak. Terraces should only be used when you want plateau-like mountains. You can apply a small value of Fractal to the entire map, to have a little realistic variation even in flat lands.

This is mostly a trial-and-error part, you need to get a feel for how strong you should apply the different effects on different areas. Generate the map often to see the result of your changes.

In the next update of this tutorial I will add:

- If you have a large map (larger than 4x4 for example), it may eventually start taking very long to generate the map, because of all the extra calculations necessary for the terrain effects you are adding. I have a workaround for this where you only generate one specific area of your map at a time, so you can still often generate the area you are editing to see how it's coming along. I'll write it down later, no time atm.

- Going to a smaller HF/DM ratio to adjust the map in detail, like polishing the shoreline to be far more accurate.

- Editing in 3D mode, and adding a Texture map with the image draqe map as a 3D texture overlay in 3D mode, adding rivers, etc.




Some random information:

Horizontal Scale for TES games:
1.8288221359252928

Vertical Scale (used when exporting from L3DT):
0.0285753458738327

Since 16-bit RAW has 65536 brightness levels, the maximum range of height difference in TES games is (65536 * 0.0285753458738327) 1872.7138671874998272 meters.

Since default water level is at 4096 Units, the default water height is (4096 * 0.0285753458738327) 117.0446166992187392 meters.

If for convenience we take the default water level in L3DT at: 0 meters
Then lowest point possible is: -117.0446166992187 meters (completely black pixel)
And highest point possible is: 1755.6692504882811272 meters (completely white pixel)

It's probably possible to use a 32-bit RAW image for your heigthmap as well, which would increase the maximum height drastically, but you most likely won't need it. Throat of the World in Skyrim is only 550 meters high, so you can at least go 3 times higher than that.

Excellent.

One quick question, when editing in the Sapphire editor, does every adjustment automatically save to the heightmap or is there an action to save the edits?

Actually I'm thinking about using Unity 3d to create the heightmap, if I can find out how to export it from unity and import it in CK. Unity's terrain creator is also very powerful and really easy to use and learn (A few hours will do)

I added a new section to the tutorial.


Sort of, the changes are stored in a memory buffer, when you close the Sapphire 3D editor, press F5 (refresh) in the Heightfield tab and the changes are applied to the heightfield image. To be sure, also save the project.


That will work, I had a look at the documentation of Unity 3d's terrain editor and you can export to RAW. You'll need to figure out the correct horizontal scale and see how the dimensions of your map convert to Skyrim though.

The editor indeed looks powerful and easy to use (very similar to L3DT's 3D mode, the confusing part of L3DT is the design map), but it lacks a generator as far as I'm aware. This is especially a shame when making fairly big maps, since you'll have to do everything by hand, and getting mountains to look realistic from scratch can be challenging.

I'm not sure if you'll be able to use an actual map as a texture overlay, but you can try adding it as a texture with tile sizes as big as your entire map.

Well that was fast, I got the link about an hour after requesting it for the editor. I would like to ask Maegfaer, I will be making a map to encompass the whole 16x16 current Oblivion heightmap grid. What settting would I need to make the correct sized map for a 16x16 quad map. Obviously not all of those 16x16 quads will eventually be imported into the game, so I presume it is possible to import into quads individual quad sized bits of the map?

Heightmaps you say? This should be incredibly helpful! I'm making my owm massive land, so I think a heightmap would save me a huge amount of time when making it. I just have to figure it out... >.>

EDIT: Oh, I see you have free and payed editions... May I ask what are the limitations of the free edition?

Oops, I keep getting an error saying "unrecognised design map algorithm"
I was trying to do a river. I set the general height at 10 and applied to all. I set it at -10 and painted in the sea. The map displays in 3d perfectly well. I then painted a -10 inland for a short way for the river estuary, then went to 0 and went inland, then to 10 and upwards to 30. I couldnt work out what you mean by draw the dry land inbetween. Is this set to relative or just set heights? Anyway then adding relative 10 I built up the high lands. I then created the map but the river didnt show as I wanted it, so I set it to -10 and drew the estuary again and upwards into the mountainside. It is always at this point that it crashes. Any suggestions?

Also how do you zoom out and in for the 3d map?

Sorry, lots of silly questions.

Yes you can import separate quads, a heightmap is just a RAW image so you can out whatever you don't need. Be aware though that a full map of 16x16 will definitely run into the 32-bit RAM limitations when the land is actually landscaped and populated. The plugins together will exceed 4GB, at which point the CK will simply crash. I estimate that the limit lies somewhere around 15x14 quads, perhaps even sooner, so indeed don't go crazy and fully develop 16x16 quads of content.

In L3DT, just make a 16x16 design map, 16384 * 16384 pixels.


The free edition is limited to loading only 2x2 quads at the same time, which is I estimate about 1/4th of Skyrim (I don't know the exact size of Skyrim, haven't looked). The Pro edition has a 3 months full trial though, so you can just use that and finish your heightmap within 3 months. Alternately you could even buy the application, it's not expensive for hobbyists.



I never had that error before? What did you save the map as (filetype)? Can you import it back in, rather than opening it? Just save your maps in the *.proj format.


Following my tutorial, you shouldn't paint the rivers itself yet, that is best done in 3D mode in the very end. What I mean, is that you start painting the land higher and higher the further you go from the coast (the closer you get to mountains). I recommend starting with following a river and going up in altitude, so that in the end when you are going to draw the river you are 100% sure that the river will be at it's highest point in the mountains, and at it's lowest point when it ends in the sea. Water tends to flow downwards, not upwards, hehe.

This is a (rather poor) example picture of how I did it with my Middle Earth map:

http://img834.imageshack.us/img834/3174/exampleip.png

Greener pixel = higher altitude. It starts low at the coast, and gets higher as it goes inland, closer to mountains. I hope this makes it a bit clearer? Going upwards along a river is just a good starting point, after that you fill in everything around it at the same height as you did the river.

EDIT: I made better examples:

This is what I mean following a river stream going upwards:
http://img593.imageshack.us/img593/5742/example1g.png

This is what I mean with filling in the surrounding flat lands at the same height (I did it partially only):
http://img408.imageshack.us/img408/8233/example2u.png


As you can see now, the land goes gradually downwards as it approaches the sea. In the end, when I'm going to draw the rivers in the 3D mode, I am sure that as I draw the river towards the sea, that the land is always going downwards, not upwards, which would cause troubles. This method seems a bit useless because these rivers went straight to the sea anyway, but if you have all kinds of curves in your rivers and don't do it this way, you might end up with up-flowing rivers in the end.


In the 3D map you can use E and R to go up and down respectively. Right click once to rotate your view point, right click again to go back to mouse mode. WASD for moving around. Space key to switch between flying and walking mode. For large maps I recommend to put the Turbo on in the tool bar for moving around fast.

I made a bunch of new screenshots from my L3DT Middle Earth map, of the Grey, Misty, Blue mountains and Erebor. They look a bit lame compared to Skyrim, but that's because of the low resolution textures (especially those normal maps, ehw). I figured I should post them here since I made this with L3DT:

http://img543.imageshack.us/img543/3538/oblivion201111290024187.png
http://img809.imageshack.us/img809/5672/oblivion201111290024360.png
http://img545.imageshack.us/img545/4439/oblivion201111290025009.png
http://img835.imageshack.us/img835/373/oblivion201111290025326.png
http://img526.imageshack.us/img526/1568/oblivion201111290025462.png
http://img35.imageshack.us/img35/7284/oblivion201111290026075.png
http://img651.imageshack.us/img651/6181/oblivion201111290026153.png
http://img507.imageshack.us/img507/2424/oblivion201111290026277.png
http://img528.imageshack.us/img528/4803/oblivion201111290026380.png
http://img593.imageshack.us/img593/1082/oblivion201111290026421.png
http://img839.imageshack.us/img839/3569/oblivion201111290027029.png
http://img33.imageshack.us/img33/7465/oblivion201111290027213.png
http://img196.imageshack.us/img196/3122/oblivion201111290028123.png
http://img694.imageshack.us/img694/6418/oblivion201111290028326.png
http://img11.imageshack.us/img11/9438/oblivion201111290029086.png
http://img827.imageshack.us/img827/2731/oblivion201111290029148.png
http://img338.imageshack.us/img338/6811/oblivion201111290029331.png
http://img197.imageshack.us/img197/6030/oblivion201111290029434.png
http://img171.imageshack.us/img171/8408/oblivion201111282357116.png
http://img202.imageshack.us/img202/4257/oblivion201111290008149.png
http://img812.imageshack.us/img812/9669/oblivion201111290008249.png
http://img717.imageshack.us/img717/994/oblivion201111290010079.png
http://img259.imageshack.us/img259/1299/oblivion201111290010369.png
http://img35.imageshack.us/img35/1188/oblivion201111290011153.png
http://img835.imageshack.us/img835/9964/oblivion201111290012186.png
http://img843.imageshack.us/img843/6316/oblivion201111290012286.png
http://img27.imageshack.us/img27/8475/oblivion201111290013084.png
http://img823.imageshack.us/img823/7941/oblivion201111290013270.png
http://img97.imageshack.us/img97/5333/oblivion201111290013424.png
http://img26.imageshack.us/img26/772/oblivion201111290014408.png
http://img408.imageshack.us/img408/7537/oblivion201111290015060.png
http://img717.imageshack.us/img717/2874/oblivion201111290015314.png
http://img62.imageshack.us/img62/6889/oblivion201111290015453.png
http://img525.imageshack.us/img525/621/oblivion201111290016070.png
http://img51.imageshack.us/img51/3375/oblivion201111290016164.png
http://img440.imageshack.us/img440/2223/oblivion201111290016270.png
http://img856.imageshack.us/img856/6136/oblivion201111290016531.png
http://img269.imageshack.us/img269/613/oblivion201111290017325.png
http://img15.imageshack.us/img15/2995/oblivion201111290018005.png
http://img64.imageshack.us/img64/6181/oblivion201111290019069.png
http://img412.imageshack.us/img412/2998/oblivion201111290020129.png
http://img37.imageshack.us/img37/8987/oblivion201111290020213.png
http://img265.imageshack.us/img265/3761/oblivion201111290020388.png
http://img265.imageshack.us/img265/5797/oblivion201111290020427.png
http://img256.imageshack.us/img256/301/oblivion201111290020568.png
http://img38.imageshack.us/img38/2862/oblivion201111290021408.png
http://img337.imageshack.us/img337/7461/oblivion201111290022131.png
http://img402.imageshack.us/img402/6044/oblivion201111290022278.png
http://img198.imageshack.us/img198/723/oblivion201111290022585.png
http://img41.imageshack.us/img41/4641/oblivion201111290023377.png
http://img823.imageshack.us/img823/507/oblivion201111290023545.png
http://img854.imageshack.us/img854/2479/oblivion201111290024112.png

Very nice, very nice indeed. Thanks for the reply, I will have another crack at the mapping today. I was wrong about the reg stuff, it was just the confirmation email of the request. Looks like I have to wait a bit.

Are they pictured within L3dt? Mine are a hideous green. I find the brown looks more workable. How do you adjust the tone?

Also to get an idea of in-game scale for city and village sizes etc. There a little green figure in the 3d window, can that be used for scaling? Is that the size of a person within the game?

Correction: Oblivion & Skyrim don't use 16bit values, they are in fact floats. What you are referring to is that maybe interchange formats only do 16bit.

No, the pictures are taken in Oblivion. The green colour in L3DT is the default, if you want pretty textures in L3DT you need to apply a http://www.bundysoft.com/docs/doku.php?id=l3dt:algorithms:cli:climate in Design map and generate the Texture Map under "Operations". The green little man should be of realistic size if your horizontal scale is correct when you started the project (it's in the tutorial), but I never use it myself so I'm not 100% sure. I personally always import the map into Oblivion now and then, to get a feel for the size at which I'm working.


You mean that WRLD data is stored internally as floats? Okay, I'll fix that. Yeah, I meant that the CS (probably CK too) exports heightmap data to 16-bit RAW, and that format is one of the most used formats for saving heightmap data in an image file. Higher is possible, but rarely ever necessary.

I'm not sure about the internal representation, but even if it would be stored as shorts you have a possible range of "+-Inf. + 16 * +-32767" per CELL, that means you can raise height in a single CELL at least 16x the datatype size, and the adjacent CELL can move the offset to that height and continue raising, so in one quad you can raise height from 0 to at least 512 * +-32767.
I'm working with CBash which exposes the height-data as floats, because they are all normalized, and normalized values can go through the roof (12 quads in TWMP => 12 * 512 * +-32767) so practically you think in terms of floats. What datatype is on disk (esm) is irrelevant as it's an interrnal representation of the compressed data. If you are curious: heightvalues are stored as deltas, "store_height = this_height - leftofme_height", so you can go up up up up up (or down down down down). The only clamped factor is slope (delta), not absolute height.

Maybe this information helps to clarify some of the technical background. Of course if you limit the interchange format to 16bit you can't do what's actually possible.

Okay, that's pretty cool to know, though it doesn't change much I think. 16-bit RAW allows for a maximum height around 1700 meters, and for example the Throat of the World, which is the highest mountain in Skyrim, is 550 meters high. My Middle Earth map which is almost 10 times larger in size has the highest mountain at around 1100 meters (900 meters compared to ground level), and I wouldn't even think of making it higher, even though I still have 600 meters left with the 16-bit RAW format.

Ok Ive obtained the program, I might actually buy it as its 24 quid UK wonga and thats fine. Looking forward to your next tutorial.

Okay, cool. Is there anything in particular that confuses you at the moment? Then I could explain that specifically.

I also uploaded a new video of my L3DT made heightmap, recorded in Oblivion. I used L3DT to actually implement the paper map I use as an overlay as a LOD texture in Oblivion itself!

http://www.youtube.com/watch?v=NjYUNsRh_so

Well currently I am practicing on a fairly large map, half the size of the ultimate aim. The program flies over it quite slowly. What size map did you do in the end for MERP?

I am toying with the settings of erosion, fractal etc etc, just to work out what they do. I could do with I suppose a bit of an idea of what is a reasonable height of mountain on your map, what is the rough mountain altitude. The highest at the moment for me is about 950 metres, but as I said its all a bit of a test at present. How long and how many tests did it take you before thinking, I reckon Ive got it?

I always used the basic heightmap editor in Oblivion so never went through importing it.
How did you manage to import the entire heightmap into Oblivion? I always found that part way into creating a large map the CS would crash because of memory limitations.

Make sure you have Turbo on in the toolbar to fly faster, and you can also use the -Clip and -Tris buttons in the toolbar to reduce the draw distance and poly detail respectively, to increase render FPS and thus movement speed drastically.

My Middle Earth heightmap is 14x14 quads, 14336*14336 pixels.


My highest mountain is around 900 compared to it's surrounding ground level. My average mountain range height is around 400-500, with peaks between 600-750 meters. Remember that Skyrim's Throat of the World is 560 meters. I can't remember exactly how much I tested, but importing the heightmap into Oblivion now and then helped a lot. Sometimes I just imported a set of 4 quads for a quick look.


You can do it through the CS, but need to restart the CS after saving a certain amount of quads or else it crashes. A far better way is to do it with TESAnnwyn, which imports the full heightmap directly flawlessly.

Ah I might try TesAnnwyn then.

Actually, yep I thought of a question. What setting do you use for your mountain creation. I have set mine as a brush of 4, peak rough at 3, fractal rough 3, terraces 3, erosion 4 (as in bars from 0).

What does each particular setting do, the erosion I get, it erodes, but fractal, peak and terrace. I know what they mean geographically but what does the program do and how much do you need to brush each area to get a good, reaslistic look?

Sorry lots of daft questions.

I'm not sure what you mean with those numbers. L3DT works with 'ratings' of 0-100, you can see them for each effect by going to "View" -> "Display effects" -> "Design map schemes..." and then picking, PeakEdit, FracEdit, etc. Very useful.

Example pictures of the different effects can be viewed http://www.bundysoft.com/wiki/doku.php?id=tutorials:l3dt:dead_rabit.

In general, Fractal should be very high on mountains (like 80-100) and hills (50-80) in my opinion, to make sure you have plenty of variation. I recommend to apply a value of 30-40 to the entire map, so even the flat areas have a little variation in them.

Erosion shouldn't be overused, use it mainly on mountains (40-60, depending on mountain type), and only quite low settings on hills (not higher than 20 imo).

Peak rough should be high for both hills and mountains (40-70), since it just creates bigger height differences (more variation), not "pointyness". Depends on how extreme you want the hills/mountains to be. For hills, Peak rough is the most important of all the effects, followed by Fractal.

Terraces/Cliff rough makes things very stair-like. It's a matter of taste, I usually apply a little to it to all my mountains (10-20) because I'm not overly fond of the effect, but it depends on what kind of environment you are making.

In general, try not to let effects end abruptly. Don't have one pixel of a rating of 80 of a certain effect be next to a pixel with a rating of 10 of that same effect, let it reduce gradually, with steps of 20-35 per pixel (though it depends on the pixel size you are working at as well, if you use a high HF/DM ratio this is not so important since L3DT will automatically interpolate it).

Just one quick Q. I worked on a set of mountains to see how they would turn out. To try a comparison turning up the settings for erosion, fractal etc I did another set of mountains and in a different session painted the new effects on to them. I did not apply to the whole map, just the new area, however when I re-do the heightmap it appears to work over the settings on the old mountain range. Is this true? Or does it only apply what has been added since? Does that make any sense? Its hard to explain.