Region Editor; how many generated objects in a cell?

[sandor]

I decided to write a few tutorials/guides concerning the landscape generation, because it's one of our main goals for ST v3.00.

RE= Region Editor.

Radius/Diameter.

Circle.


Cell sizes.

In Morrowind, the cell size was 8192x8192 i.e. 8k by 8k. An Oblivion cell is 4096x4096 i.e. 4k by 4k - which is a quarter of the size of a Morrowind cell.



Generating objects, how many objects in a cell?

I assume we generate one object for the region area (e.g. a rock).

If we talk about a radius of 500 units, it's one eight of the length of the side of an Oblivion cell. The "Radius" gives an idea of the distance, in units, that we require between one object and another object.

If we specify a radius ® of 50 units, the distance between every rock has to be 2*50 units (two times the radius). The area formula for a circle "PI*R^2" would comply to this requirement. To simplify, we'll call the area (R*2)^2, where R*2 is the diameter. Oblivion objects are bounded by a cube, so the diameter is a good estimate.

The "Density" defines how many objects we want to have in a cell.
The higher the number --> The higher the number of objects.


This formula has to be used.

------> N = (L/(R* 2))^2 * D

• N indicates the approx. number of objects generated in a cell
  
• R indicates the radius of an object
  
• L indicates the length of the side of a Oblivion cell == 4096 units
  
• D indicates the Density value
  

For example we use a Radius of 50 and a Density of 5% (screenshot).


(4096/(50*2))^2 * 5/100 ----> N == 83.886 per cell.

If we use two different (or more) objects with a different radius and density setting the formula would be complex.

This guide helps to explain how radius and density settings work in general.



I would like to thank Dave Foster for his ideas concerning this subject.

[SACarrow]

What might be useful as well would be a post listing some values for preferred densities of certain types of objects (rocks, tress and the like) using that equation. I think that would make for easier lookup for landscape n00bz like myself.

Just a thought,
Steve

[blackbird]

My preferred densities are for
large rocks (big radius): ranging from 20 to 90
small rocks (small radius): > 5
trees: from 10 to 30
flora: >3, also dependant on radius
tewtures: the main one shoould be 100 or at least 50, unless you are putting a lot of textures.

I should use some parent statics or items. A parent's purpose is that all the child objects will be generated around the parent. Example: An oak tree with some mushrooms in the neighbourhood and some small rocks also. The parent is the tree and the mushrooms and the rocks are the children. To make a parent, you drag the mushroom in the box to the oak tree. if succesful done, you can see box where it will be asked to fill in the radius parent size The bigger the parent radius size, the more mushrooms and rocks can be generated around the tree. I'll stop by now, so that sandor can explain more and fill in the details.

Another thing form my experience is that the priority is given to the highest ranked items.
Use randomness (change the values in the 3th tab) for your final generation, like the size or angle. Trees can't be rotated.
Use a vertex shading for trees and rocks.
Rocks may be sinked and set to confrom to slope also.

[TheImperialDragon]

I think this tutorial will help give new modders a good idea about how region generating works. :goodjob:

Originally posted by SACarrow
What might be useful as well would be a post listing some values for preferred densities of certain types of objects (rocks, tress and the like) using that equation. I think that would make for easier lookup for landscape n00bz like myself.

Just a thought,
Steve

You'd have to consider the type of region you're generating or the number of other objects you've got in the area.

[SACarrow]

Originally posted by TheImperialDragon
IYou'd have to consider the type of region you're generating or the number of other objects you've got in the area.

Please discuss these considerations if you will, O Mighty Landscaper. It is these insights from those like you, sandor and blackbird that will make it easier for more people to landscape prior to 3.0.

Steve

[TheImperialDragon]

Originally posted by SACarrow
Please discuss these considerations if you will, O Mighty Landscaper. It is these insights from those like you, sandor and blackbird that will make it easier for more people to landscape prior to 3.0.

Steve

The equation at the beginning is if there's only one object in the whole region.

If we use two different (or more) objects with a different radius and density setting the formula would be complex.

The best way to understand it is to experiment a little bit, at least that's how things usually are for me. Well, maybe with the help of a few written explanations as well.