►Images
▼4 Floating-Point Bitmaps
On this page:
flomap-gradient-x
flomap-gradient-y
flomap-gradient
flomap-gradient-normal
  top  ← prev  up  next → 

4.6 Gradients and Normals

procedure

(flomap-gradient-x fm) → flomap

  fm : flomap

procedure

(flomap-gradient-y fm) → flomap

  fm : flomap
These return, per-component, estimates of the local x- and y-directional derivatives using a 3×3 Scharr operator.

procedure

(flomap-gradient fm) → 
flomap flomap
  fm : flomap
Equivalent to (values (flomap-gradient-x fm) (flomap-gradient-y fm)).

Examples:

> (define-values (dx-fm dy-fm)
    (flomap-gradient (flomap-drop-components fm 1)))
> (values (flomap->bitmap (fm* 0.5 (fm+ 1.0 dx-fm)))
          (flomap->bitmap (fm* 0.5 (fm+ 1.0 dy-fm))))

image

image

procedure

(flomap-gradient-normal fm) → flomap

  fm : flomap
Given a one-component flomap, returns a 3-component flomap containing estimated normals. In other words, flomap-normal converts height maps to normal maps.

Examples:

> (flomap->bitmap sine-fm)

image

> (flomap->bitmap (flomap-gradient-normal sine-fm))

image

> (flomap-gradient-normal fm)

flomap-gradient-normal: expected argument of type <flomap

with 1 component>; given: (flomap (flvector 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0...

  top  ← prev  up  next →