Fisheye Camera for Cycles

For sample images see:
http://www.dalaifelinto.com/?p=399 (equisolid)
http://www.dalaifelinto.com/?p=389 (equidistant)

The 'use_panorama' option is now part of a new Camera type: 'Panorama'.
Created two other panorama cameras:

- Equisolid: most of lens in the market simulate this lens - e.g. Nikon, Canon, ...)
             this works as a real lens up to an extent. The final result takes the
             sensor dimensions into account also.
             .:. to simulate a Nikon DX2S with a 10.5mm lens do:
                 sensor: 23.7 x 15.7
                 fisheye lens: 10.5
                 fisheye fov: 180
                 render dimensions: 4288 x 2848

- Equidistant: this is not a real lens model. Although the old equidistant lens simulate
               this lens. The result is always as a circular fisheye that takes the whole sensor
               (in other words, it doesn't take the sensor into consideration).
               This is perfect for fulldomes ;)

               For the UI we have 10 to 360 as soft values and 10 to 3600 as hard values (because we can).


Reference material:
http://www.hdrlabs.com/tutorials/downloads_files/HDRI%20for%20CGI.pdf
http://www.bobatkins.com/photography/technical/field_of_view.html

Note, this is not a real simulation of the light path through the lens.
The ideal solution would be this:
https://graphics.stanford.edu/wikis/cs348b-11/Assignment3
http://www.graphics.stanford.edu/papers/camera/


Thanks Brecht for the fix, suggestions and code review.
Kudos for the dome community for keeping me stimulated on the topic since 2009 ;)

Patch partly implemented during lab time at VisGraf, IMPA - Rio de Janeiro.

1 files changed, 51 insertions, 0 deletions

diff --git a/intern/cycles/kernel/kernel_montecarlo.h b/intern/cycles/kernel/kernel_montecarlo.h
index 68f007cfd97..3fb4d41ce06 100644
--- a/intern/cycles/kernel/kernel_montecarlo.h
+++ b/intern/cycles/kernel/kernel_montecarlo.h
@@ -224,6 +224,57 @@ __device float3 equirectangular_to_direction(float u, float v)
 		cos(theta));
 }
 
+/* Fisheye <- Cartesian direction */
+
+__device float3 fisheye_to_direction(float u, float v, float fov, Ray *ray)
+{
+	u = (u - 0.5f) * 2.f;
+	v = (v - 0.5f) * 2.f;
+
+	float r = sqrt(u*u + v*v);
+
+	if (r > 1.0) {
+		ray->t = 0.f;
+		return make_float3(0.f,0.f,0.f);
+	}
+
+	float phi = acosf((r!=0.f)?u/r:0.f);
+	float theta = asinf(r) * (fov / M_PI_F);
+
+	if (v < 0.f) phi = -phi;
+
+	return make_float3(
+		 cosf(theta),
+		 -cosf(phi)*sinf(theta),
+		 sinf(phi)*sinf(theta)
+	);
+}
+
+__device float3 fisheye_equisolid_to_direction(float u, float v, float lens, float fov, float width, float height, Ray *ray)
+{
+	u = (u - 0.5f) * width;
+	v = (v - 0.5f) * height;
+
+	float rmax = 2.f * lens * sinf(fov * 0.5f);
+	float r = sqrt(u*u + v*v);
+
+	if (r > rmax) {
+		ray->t = 0.f;
+		return make_float3(0.f,0.f,0.f);
+	}
+
+	float phi = acosf((r!=0.f)?u/r:0.f);
+	float theta = 2.f * asinf(r/(2.f * lens));
+
+	if (v < 0.f) phi = -phi;
+
+	return make_float3(
+		 cosf(theta),
+		 -cosf(phi)*sinf(theta),
+		 sinf(phi)*sinf(theta)
+	);
+}
+
 /* Mirror Ball <-> Cartesion direction */
 
 __device float3 mirrorball_to_direction(float u, float v)