When someone first gets Fractal Terrains, they are immediately amazed by the beautifully detailed random worlds it creates. Mesmerized, they cycle through one random world after another. They play with settings to create different types of worlds. Eventually, they find one that speaks to them. It is nearly perfect, except for just a few things. So they sit down to tackle the editing portion of the program.

The basic commands allow you to Raise/Lower: Land Offset, Prescale Land Offset, Roughness/Smoothness, Rainfall, Temperature, etc. I suspect most people don’t initially care about temperature and humidity. They want to change the altitude of the terrain. Land Offset seems like an intuitive place to start. What is this Prescale Land Offset anyway? It sounds scary and confusing. Let’s leave that one alone.

So our new user zooms in somewhere and starts playing with the tools. But there is no basis for selecting a brush size or how much to raise/lower the land by. Eventually, they mess up a section and try to fix it with the same tools. Whatever they do, it keeps getting worse. Sooner or later, frustration sets in. They set it aside and go do something else, all too often never to return.

Reading the forums, that seems to be a pretty standard sequence of events. It’s a shame, because FT3 really is an amazing program. It isn’t especially intuitive and I think that’s what trips up most people. But with just a few simple tips, I think new people can easily be put back on track.

First off, use one of the fractal functions with Perlin Improved Noise in the name. Second, increase editing size (4000+). Third, set the Undo slider all the way up (1500 iirc). Fourth, use a big brush set to make small changes. But most importantly of all, enable Prescale Offset Editing and use it instead of Normal Offset Editing.

So what’s the difference? The short answer is that Prescale Offset Editing applies the changes prior to scaling. Don’t worry if that doesn’t clear things up. What it really means is that editing will work better and you will be happier with the results. The one thing you have to get used to is that units are now more arbitrary. Whereas normal offset editing raised or lowered terrain by however many feet/meters you entered, Prescale Offset Editing uses units primarily between 0 and 1. After a short time you will get a feel for how much you need in a given situation and it will become second nature.

If you want a more detailed explanation, here is a comment I found on one of the forums, made by the author of the program (emphasis mine):

The prescale offset was a relatively late addition to FT. It’s probably how the painting tools should have worked in the first place, but the problem is that it’s a non-linear effect defined in a non-intuitive fashion. FT computes altitudes according to the following equation:

altitude = (fractalfunction + prescale) ^ exponent * scale * roughness + offset


# fractalfunction is the fractal function that’s the basis of the world (it usually gives a result in the 0 to 2 range)

# prescale is the prescale offset editing value that can be painted or set. This value will usually be pretty small, on the order of -1 to +1

# exponent is the non-linear adjustment used to get the continental shelves. It is usually around 2 for areas above the shelf level and 1/2 for areas below it. FT doesn’t provide a way to directly edit this value

# scale converts the output of the fractal function to the final world range. The way to control this value in FT is to set the Highest Peak and Lowest Depth values in the World Settings property sheet.

# roughness is the roughness editing value that can be painted or set. This value will usually be pretty small, on the order of 0 to 2 (the default is 1). A value of 0 “turns off” the fractal parts of the world and a value of 1 shows the full normal fractal world. A “blank world” is a world where the roughness is set to 0. As you raise the roughness from 0, the fractal parts show through, lowering your land if there is ocean in the fractal and raising it if there is land in the fractal.

#offset is the roughness editing value that can be painted or set. This value is defined in world units (meters or feet) and is linearly defined. It’s the simplest to understand and easiest for the software to work with. The big problem with it is that it fights with the continental shelves. But, most of the fancier tools like fill basins, incise flow, and several of the others work exclusively with this channel. It would be nice if they worked with the prescale channel, but they don’t.

For roughening up the surface without involving the fractal function, consider the Tools>>Global Noise operation.

– Joe Slayton

Maybe that helps clear things up, maybe not. Understanding the math really isn’t that important. What is important is that Prescale Offset Editing will make your life much easier!

Another comment I found somewhere implied that the primary function was for dealing with continental shelves. While that certainly isn’t the only place it helps, Prescale Offset Editing is essential when editing coastlines when continental shelves are enabled. Here is an example of the difference between normal and prescale offset editing on a coastline:


Normal Offset Editing

Prescale Offset Editing

As you can see, there is an incredible difference between the two. Prescale Offset Editing is clearly the way to go there.

Unfortunately, many of the more advanced editing commands still work through the normal offset editing layer. Hopefully, when the next FT3 Update patch comes around, all those commands will have gotten a re-write and everything will use the Prescale Offset Editing channel instead. Naturally, development dollars follow user support, so get on the forums and let ProFantasy know how much you love Fractal Terrains and how much you want to see continued development! That’s the fastest way to get changes like that made.

Obviously, this is one of my favorite programs. But I still have an ever-growing wish list of new/updated features I’d like to see added. Hopefully, getting people to use Prescale Offset Editing will help get them over the initial learning curve and increase support for the program in general. I’d love to see FT3 get as much development time as CC3 and the other add-ons.