Quote Originally Posted by Redrobes View Post
I'll keep an eye on your progress. I wrote a geomorphological erosion app and some others, like say, Waldronate, also write apps which do erosion and other geological processes. I wont comment too much at this stage as id like to see more where you are heading. But I would say that I think its hard to go from shorelines to 3D terrain. Its very easy to go from 3D to shorelines however. So I think you may have to model your plate tectonics in 3D and do your simulation like that and then export maps in 2D from them rather than to do it in 2D shapes to create 3D elevation models. But I am up for seeing new ways of doing things.

Ok, yeah I only mentioned shorelines as an example of one piece of what I need to do, I will have collisional and extensional information as well and as I mentioned a model for uplift of mountains and isostasy. For the Mesozoic and beyond there is additionally dynamic topography but the jury is out on the ultimate effect of that relative to isostasy (you're talking maybe 500m of dynamic topography max in either direction and often quite less, compared to say 5000m isostatic uplift of thickened crust in say the Andean Altiplano or Tibetan Plateau. And what I'm not modeling from plate tectonics movements, there is a load of geological information out there for palaeo mountain ranges.

So the 3D component will be there. Basically I am going to have a grid of points associated with individual pieces of the earth's crust, which at any given point in time will also have a z-dimension which changes over time. A digital elevation model is essentially 3D, since you have x-y coordinates and then the height or 'color' is the third dimension. In my case, it will be a '4D' DEM.

I am only going to go back as far as perhaps 2 Ga, because there is no evidence plate tectonics existed in the way that it does further than that, and some people believe it only started in earnest in the late Neoproterozoic. I don't want to guess at models for the Archean, for which there is very little geological data anyway. Even 2 Ga may be overambitious, but I have a personal interest in Mesoproterozoic North America, so I am going to do my best.

Because erosion and the 'form' of a given landform changes so rapidly in comparison to the long march of geological time, it's unrealistic to produce a 'real-time' physical geography that changes at a realistic rate compared to say, plate motion and deformation. (Imagine a 10-minute animation of plate tectonics animations starting from say 2 Ga, the modern form of many mountain ranges, for example, has only been such since the Pleistocene and the last Glacial Maximum, which is approximately just 0.1% of the whole animation representing 2 Ga, or 6/10 of a second! If mountains had to be sculpted continuously every half second, it would be a very distracting animation to say the least, although it may be pretty interesting to see the effect). So I will basically be exaggerating the duration of the form of a given landscape in order to showcase the bigger picture of tectonic history and the quality of the land over a longer duration of time. (same goes for climate, which if I was incorporating realistic changes by milankovitch cycles, would be changing faster than the frame rate of the animation). And rivers for instance change even more rapidly - if their change was scaled realistically relative to geological time, they would but be an ephermal blur on the landscape, a vibrating, dendritic hallucination.

To put it simply, I am going to be exaggerating the duration of landforms relative to geological time, for the sake of clarity, so I suppose the physical features will be mostly symbolic than purely simulated, that is it will communicate something more like 'there were river systems here going from the NE to the SW for ~20 Ma', or 'a mountain range uplifted and then was peneplained over the course of 60 Ma' instead of 'this is a simulation of what the area looked like this specific time'. I am really just interested in telling the bigger picture story, but with realistic looking physical geography.

Thinking about it, though, if I develop these land-sculpting processes in such a way that I can control the rate at which they occur with any given run of the model, it would be interesting to render it both at the 'big picture' rate that I describe above as well as a 'realistic' rate just to see what happens, maybe the earth will seem like it is breathing or decaying like a timelapse video of decomposing fruit. :p