Annoying/Frustrating problem...

[preypacer]

Hello..

So, I've spent a good deal of time tracing out my continent map and getting it to where the shorelines are really close to the drawn version, but still look very natural (not blocky, etc).

I have the overall landmass set at 5 meters above sea level with sea level itself at -1 meter (just a little extra space to play with on shorelines, etc). The only place there was water was the ocean area, and a couple deliberate lakes I placed when "tracing" the detail map. I added a very little bit of fractal noise just so the map wouldn't be completely flat. I kept undoing and re-doing 'til the range was from about 2m to 7m above sea level - plenty high enough to maintain a solid landmass.

Satisfied with the overall landmass, I decided it was time to go ahead and start "filling in" the major land features, and so, I decided to start with the ocean surrounding the map. I painted in, I believe... 4 levels.. starting from about -5 to -10, then -20, then -40, etc. I painted fractal noise and erosion around it all so that it would slope a bit more realistically, etc. And the resulting heightmap in those areas looked great.

However, it seems that editing the water areas has screwed up the rest of the map as well as I now have lakes all over the place and spots on the landmass that go as deep as -17 meters below sea level.

Mind you, I painted these on with the "pencil" tool. I didn't do "Apply to All". Not even accidentally.

I've "undone" the changes to the ocean and re-created the height map, finding that it would go back to the way I wanted it. Then I'd paint in ocean again on the detail map, reprocess the heightmap and, again... same thing, lakes everywhere. It seems to magnify the "noise" effect across the entire land mass, even though I'm painting it only in the oceanic areas.

Is there some kind of a bug with that tool, or is that some kind of "necessary" effect of applying erosion/nose to even a specific area of the map?

Thanks...

[Telarus]

+It seems to magnify the "noise" effect across the entire land mass, even though I'm painting it only in the oceanic areas.+

By deepening the low end of your elevation range without raising the upper end, you've probably shifted all of the results of the erosion "downwards" (or as you said, 'magnified' it). Try adding a large hill in one area of your map, to balance the ocean depth (easier to edit out than all the little "holes").

Other than that, you could start with the original map (before your ocean edits), and then go to "Height-field -> Change vertical range" and play with the Histogram operations (bottom 3 values):

If you just change Average Altitude, it shifts the sea level up or down.

Changing just Altitude Range will squish or stretch the total range (but keep the other ratios where they were).

Changing just % above Sea Level will shift the total range up or down.

These should allow you to raise or sink the landmass to your taste.

Or you could just raise the lower end slightly to squish those areas back above sea level.

[preypacer]

+It seems to magnify the "noise" effect across the entire land mass, even though I'm painting it only in the oceanic areas.+

By deepening the low end of your elevation range without raising the upper end, you've probably shifted all of the results of the erosion "downwards" (or as you said, 'magnified' it). Try adding a large hill in one area of your map, to balance the ocean depth (easier to edit out than all the little "holes").

Other than that, you could start with the original map (before your ocean edits), and then go to "Height-field -> Change vertical range" and play with the Histogram operations (bottom 3 values):

If you just change Average Altitude, it shifts the sea level up or down.

Changing just Altitude Range will squish or stretch the total range (but keep the other ratios where they were).

Changing just % above Sea Level will shift the total range up or down.

These should allow you to raise or sink the landmass to your taste.

Or you could just raise the lower end slightly to squish those areas back above sea level.

So any time you increase or decrease the terrain's overall height range in one spot, it affects the entire map?

Yikes lol.

You know... that does sorta give possible meaning to something I saw someone do in a video using L3DT, though. It didn't make sense at the time, but now... if that's what it was.. then it does. Basically, at the start of the video, he places a really tall spike, off on its own in one corner of the map. He was doing this in the heightmap editor, mind you. But perhaps that was done in order to sort of "set" the elevation and limit any such changes beforehand? Or,perhaps it's just a marker to keep his bearings on North, South, etc... Maybe both.

Here's the vid: http://www.youtube.com/watch?v=HJwL1FIMr5o

He does some really nice work in it, incidentally.

[Aaron]

Hi Preypacer,

So any time you increase or decrease the terrain's overall height range in one spot, it affects the entire map?

No, it doesn't. There may be some localised effects, such as increased erosion run-off in the surrounds, but there are no global effects to worry about.

That sort of behaviour is common in applications that use fixed-point representations of heightfields (e.g. Torque). Users of L3DT may occasionally set some high/low pixels to 'make room' in the fixed-precision height range, but this is for the benefit of those other programs, and is not necessary or useful in L3DT itself.

Anyway, back to your issue. I think it's due to the noise overlays and/or erosion. Because you're using relatively small heights above sea level (e.g. 5m), even mild levels of noise or erosion could bump areas below 0m. Noise will displace terrain up or down in a random fashion, with a magnitude dependent on the chosen noise strength. If the affected terrain is sloping, erosion will also reduce it's height, which will be deposited on flat terrain downstream.

Cheerio,
Aaron.

[preypacer]

Hi Preypacer,

So any time you increase or decrease the terrain's overall height range in one spot, it affects the entire map?

No, it doesn't. There may be some localised effects, such as increased erosion run-off in the surrounds, but there are no global effects to worry about.

That sort of behaviour is common in applications that use fixed-point representations of heightfields (e.g. Torque). Users of L3DT may occasionally set some high/low pixels to 'make room' in the fixed-precision height range, but this is for the benefit of those other programs, and is not necessary or useful in L3DT itself.

Anyway, back to your issue. I think it's due to the noise overlays and/or erosion. Because you're using relatively small heights above sea level (e.g. 5m), even mild levels of noise or erosion could bump areas below 0m. Noise will displace terrain up or down in a random fashion, with a magnitude dependent on the chosen noise strength. If the affected terrain is sloping, erosion will also reduce it's height, which will be deposited on flat terrain downstream.

Cheerio,
Aaron.

Hmm... Then I'm not sure I understand what's going on.

When I mouse over those areas on the DM, the elevation still shows at 4-5 meters and I still have the sea level set a -1m, so there shouldn't be anything. There's no lakes there either.

Here's the thing, the map was consistently fine in "build" after "build" prior to me adjusting the elevation of the areas below sea level. Originally, I had the entire water area set to -10m. I could raise certain areas (I did so to place in some small "test" mountains) and it didn't affect anything. It's not until I went around and manually painted in deeper sea elevations that this problem started.

Now, nothing I do is fixing it. I went in and increased the DM pixels in those spots to 8m... I reprocessed the heightmap, and those spots are still way too low and filled with water.

I don't have it set to auto-flood lakes or anything, so that shouldn't be it either.

To indulge in a bit of personification, L3DT seems to be "refusing" to change those specific spots.

I'm doing another full map "build" as I type this so I can see what's going on in sapphire.

Is there a way I can upload a file here that you can maybe check out to see if you can figure out what the issue is? At this piont, I'm thinking I'll have to start from scratch and re-draw the entire map again... which I'm not really wanting to do lol.

[Aaron]

Hi Preypacer,

When I mouse over those areas on the DM, the elevation still shows at 4-5 meters and I still have the sea level set a -1m, so there shouldn't be anything. There's no lakes there either.

The height values in the design map are the starting point for the heightfield, not the end point. Noise, erosion and other overlays act on these initial heights to produce the output heightfield. If the strength of the overlay effects are set to a high values, the output heightfield will deviate further from the initially designed hight. Erosion, in particular, can knock hundreds of metres off mountain slopes when carving valleys. If you want the output to exactly match your design, you need to set the strength of these overlays to zero.

Since your maps have very low altitude ranges (<100s of metres), the overlay effects are probably overpowering your underlying design. I'd recommend you use the design map brush to set the fractal and peak noise, erosion and terraces all to 0 in/around the affected areas to see if this fixes the problem. If it does fix the problem, you may then want to reintroduce a small amount of these overlays to improve the 'naturalness' of the output, stopping short of the point where it causes the output to deviate unacceptably from your intended design.

At this piont, I'm thinking I'll have to start from scratch and re-draw the entire map again

I doubt that will help; you'll just get to the same point again. It would be better to understand why your changes are not having the desired effect, and what changes you should be making to achieve said outcome. Can you post a screenshot of the design map and of the heightfield? You can use the 'upload attachment' button in the forum for this.

Best regards,
Aaron.