Per my previous post I now seem to be able to reliably load my data and add oceans.
This morning started with me following Cyphyr's advice of a load directly from the shader into the compute terrain node. I started with a small file covering an island (1000x1000pixels) to test it and it worked perfectly in that it gave me a clear image of the island BUT it only gave me some small bumps where it existed.
I adjusted the "Displacement Amplitude" up and the terrain popped out nicely. I then rescaled the map from my 1000 x 1000 to 2000 x 2000 and found that I needed to increase the amplitude again to keep the heights. By the time I increased the scale to 10k x 10k the amplitude needed to be >1000 to show any meaningful height...and 2000 was better. This indicated what I'd been doing wrong previously when I only set amplitude up by a few hunderd on a 10kx10k map.
At this point I tried loading my original TIF (10k square) and set amplitude to 2000 - it showed up OK as long as I had all other seetings as per dunes screenshots.
Subsequently I found some limitations to Cyphers approach for what I wanted as it (obviously in retrospect) does not give me access to the heightfield operators such as erode, resize and adjust vertical which I'd learned and knew how to operate to give me the look of the terrain I wanted.
I then followed the approach oultined by Dune and pointed my Shader into the Heightfield Generate node, shader input and after hitting "generate" (
) I had the terrain loaded as a 10k heightfield - and no crashes at all thus far!!! Anyone new reading this, make sure you ensure the dimensions in the shader are exactly the same as the dimensions in the generate...otherwise you may not see the terrain you're looking for (it being offset from the bounding box)...and dont forget to hit "Generate Now" after each change. Also, un-check the "Flatten Surface first" option on the Displacement tab of the "Heightfield shader 01" as shown
Next I decided to increase the size to 2900km sq...and hit my first crash. To be fair, I'd probably run 10-20 variations, loads, resizes etc, so I restarted the application and loaded the last set of settings and it loaded OK.
Next I wanted to load the oceans. Before doing so I looked at the height of the black areas of my map - which should always be below sea level, however (I assume due to the spherical nature of the planet) I noted that from the centre point, the height of the lowest point varied the further I went from that centre-point (for newbies, the problem is worse if you load the image from the "Lower Left" as you now have to deal with the curvature of the earth over 2900km rather than half that distance). To counter the problem I changed the radius of the planet (Objects>Planet 01) from the default 6.378e+006 to 6.378e+009 to effectively make the surface 'flat' over a 2900km distance. Not sure what impact this will have on the atmosphere/sunset etc later,...but I'll sort that out later. Would love to hear if there's some smarter (easy) solution...I did read on the forum, someone projecting the image spherically from the centre of the planet, but the description of how that was actually done was pretty sparse and I couldnt follow it.
Now that I had my sea level relatively flat, I played safe by loading in 4 x lakes of 500k-700k radius just in case this put less load on the memory/app. That seemed to work OK. . I've now saved my map, with all relevant settings as shown in the attached (those NOT new to this will find it mundane, but anyone new and trying to do the same thing may be interested to see my settings).
Now to try some erodes (may go to another app based on other recommendations), adjust the heights and do some smoothing before I start colouring it in....oh yeah, and try to define the rivers (currently a 1 pixel black trench drawn in my TIF).
