## Random distance field image thread

**category:**code [glöplog]

Now you know how to properly greet mercury.

In order to annoy you guys not too much: All these old spikeball showing screenshots are nothing we are currently working on.

las: that makes me sad :(

(O_O)

can anyone please tell me when distance fields where first invented?

and presumably by whom?

@unc Cries.

... Has new wallpaper.

... Has new wallpaper.

but i just put on these pants!

unc: Wow! I love the second one.

@unc !! also, /r/ fullhd

unc wins the thread.

rudi: Distance fields are a pretty old thing, I guess really old - given that it's just a scalar field with some constraints.

There are several different methods to extract the surface from the (S)DF e.g. bisection, marching cubes/tetrahedrons, sphere tracing (which is what people here call "raymarching" - just another not properly defined term like "ray casting" (try to find a proper definition! :D)).

John C. Hart

Sphere Tracing: A Geometric Method for the Antialiased Ray Tracing of Implicit Surfaces (1994)

unc: how do you do the blurring/fake DoF?

There are several different methods to extract the surface from the (S)DF e.g. bisection, marching cubes/tetrahedrons, sphere tracing (which is what people here call "raymarching" - just another not properly defined term like "ray casting" (try to find a proper definition! :D)).

John C. Hart

Sphere Tracing: A Geometric Method for the Antialiased Ray Tracing of Implicit Surfaces (1994)

unc: how do you do the blurring/fake DoF?

**Quote:**

extract the surface

extract/intersect...

unc: can't wait to see it running in realtime.

unc: the second shot looks like it was taken with a real camera. The "lens" producing chromatic aberrations.... :)

las: ok. thanks. what ive seen from figures and things like that from SDF's is that when the sphere hit's and object, the ray starts on the radius (that is jumps), and then continues the ray along the direction, is that the trick? i just think that iq's NVScene slides where kinda difficult to grasp at fist sight. i thought the red lines where other rays, but i guess its just showing radius-distance and hasn't really anything practial use in the sence of the directions? :P

Rudi: that's it. You calculate the distance to the closest surface from the current point, then you know it's safe to move the ray by that distance in any direction.

And of course the surface of a sphere is the same distance from the centre in any direction, so you could also say that you calculate the intersection with the nearest surface and a sphere with the centre at the current location, then move the ray to the surface of the sphere. Which is slightly more confusing, but sometimes useful :)

And of course the surface of a sphere is the same distance from the centre in any direction, so you could also say that you calculate the intersection with the nearest surface and a sphere with the centre at the current location, then move the ray to the surface of the sphere. Which is slightly more confusing, but sometimes useful :)