diff --git a/examples/direct/direct.go b/examples/direct/direct.go
index 8adc804..5d44648 100644
--- a/examples/direct/direct.go
+++ b/examples/direct/direct.go
@@ -11,6 +11,7 @@ import (
 	"github.com/hunterloftis/pbr/surface"
 )
 
+// The pathological case for indirect lighting: a small, very bright light at a large distance
 func main() {
 	floor := surface.UnitCube().Move(0, -1, 0).Scale(100, 1, 100)
 	halogen := material.Light(10000000, 10000000, 10000000)
diff --git a/examples/moses/moses.go b/examples/moses/moses.go
new file mode 100644
index 0000000..b83a7b3
--- /dev/null
+++ b/examples/moses/moses.go
@@ -0,0 +1,37 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/hunterloftis/pbr"
+	"github.com/hunterloftis/pbr/material"
+	"github.com/hunterloftis/pbr/obj"
+	"github.com/hunterloftis/pbr/surface"
+)
+
+func main() {
+	moses, err := obj.ReadFile("fixtures/models/moses/model.obj", false)
+	if err != nil {
+		panic(err)
+	}
+	key := surface.UnitSphere(material.Light(100000, 100000, 50000)).Move(-20, 10, 20).Scale(5, 5, 5)
+	fill := surface.UnitSphere(material.Light(20000, 20000, 50000)).Move(30, 10, 5).Scale(5, 5, 5)
+	back := surface.UnitSphere(material.Light(25000, 25000, 100000)).Move(-30, -5, -10).Scale(8, 8, 8)
+	scene := pbr.NewScene(moses...)
+	bounds, _ := scene.Info()
+	target := bounds.Center
+	scene.Add(key, fill, back)
+	cam := pbr.NewCamera(888, 500).MoveTo(0, -10, 50).LookAt(target, target)
+	render := pbr.NewRender(scene, cam)
+	interrupt := make(chan os.Signal, 2)
+
+	fmt.Println("rendering moses.png (press Ctrl+C to finish)...")
+	signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)
+	render.Start()
+	<-interrupt
+	render.Stop()
+	render.WritePngs("moses.png", "moses-heat.png", "moses-noise.png", 1)
+}
diff --git a/examples/shapes/shapes.go b/examples/shapes/shapes.go
index 052098d..0d9eb56 100644
--- a/examples/shapes/shapes.go
+++ b/examples/shapes/shapes.go
@@ -3,7 +3,9 @@ package main
 import (
 	"fmt"
 	"math"
-	"time"
+	"os"
+	"os/signal"
+	"syscall"
 
 	"github.com/hunterloftis/pbr"
 	"github.com/hunterloftis/pbr/geom"
@@ -18,7 +20,7 @@ func main() {
 	whitePlastic := material.Plastic(1, 1, 1, 0.2)
 	bluePlastic := material.Plastic(0, 0, 0.9, 0)
 	greenPlastic := material.Plastic(0, 0.9, 0, 0)
-	gold := material.Metal(1.022, 0.782, 0.344, 0.9, 0)
+	gold := material.Metal(1.022, 0.782, 0.344, 0.1, 1)
 	greenGlass := material.Glass(0.2, 1, 0.1, 0.05)
 
 	scene := pbr.NewScene()
@@ -42,9 +44,11 @@ func main() {
 		surface.UnitSphere(gold).Move(0.45, 0.05, -0.4).Scale(0.2, 0.2, 0.2),
 	)
 
-	fmt.Println("rendering shapes.png (15 mins)...")
+	interrupt := make(chan os.Signal, 2)
+	fmt.Println("rendering shapes.png (press Ctrl+C to finish)...")
+	signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)
 	render.Start()
-	time.Sleep(time.Minute * 15)
+	<-interrupt
 	render.Stop()
 	render.WritePngs("shapes.png", "shapes-heat.png", "shapes-noise.png", 1)
 }
diff --git a/geom/direction.go b/geom/direction.go
index d6c1005..b4d5d2b 100644
--- a/geom/direction.go
+++ b/geom/direction.go
@@ -52,6 +52,7 @@ func (a Direction) Scaled(n float64) Vector3 {
 }
 
 // Cross returns the cross product of unit vectors a and b.
+// TODO: Has floating point error - acceptable?
 func (a Direction) Cross(b Direction) Direction {
 	return Direction{a.Y*b.Z - a.Z*b.Y, a.Z*b.X - a.X*b.Z, a.X*b.Y - a.Y*b.X}
 }
diff --git a/material/map.go b/material/map.go
index 6de8014..d4143d9 100644
--- a/material/map.go
+++ b/material/map.go
@@ -95,9 +95,8 @@ func (m *Map) At(u, v float64) *Sample {
 			y += height
 		}
 		r, g, b, a := m.d.Texture.At(x, y).RGBA()
-		// fmt.Println("rgb:", r, g, b, a)
-		// panic("ok")
 		s.Color = rgb.Energy{float64(r), float64(g), float64(b)}.Amplified(1 / float64(a))
+		// TODO: deal with metals; s.Fresnel = s.Fresnel.Blend(s.Color, s.Metal)?
 	}
 	return s
 }
diff --git a/obj/scanner.go b/obj/scanner.go
index e24fe2d..4041952 100644
--- a/obj/scanner.go
+++ b/obj/scanner.go
@@ -36,7 +36,7 @@ func NewScanner(r io.Reader) *Scanner {
 		vn:      make([]geom.Direction, 0),
 		vt:      make([]geom.Vector3, 0),
 		lib:     make(map[string]*material.Map),
-		mat:     material.Plastic(1, 1, 1, 0.7),
+		mat:     material.Default,
 	}
 }
 
diff --git a/sampler.go b/sampler.go
index 987afb7..9dceedd 100644
--- a/sampler.go
+++ b/sampler.go
@@ -42,6 +42,8 @@ func (s *sampler) start(buffer *rgb.Framebuffer, in <-chan int, done chan<- samp
 	}()
 }
 
+// TODO: sample Specular reflections from direct light sources and weight results by their BSDF towards the light
+// Or, better, sample lights directly in general and pass that through a unified BSDF
 func (s *sampler) tracePrimary(x, y int, rnd *rand.Rand) (energy rgb.Energy) {
 	ray := s.camera.ray(float64(x), float64(y), rnd)
 	hit := s.scene.Intersect(ray)
@@ -84,8 +86,7 @@ func (s *sampler) traceIndirect(ray *geom.Ray3, depth int, signal rgb.Energy, rn
 	normal, mat := hit.Surface.At(point)
 	energy = energy.Merged(mat.Light, signal)
 	dir, strength, diffused := mat.Bsdf(normal, ray.Dir, hit.Dist, rnd)
-	lights := s.scene.Lights()
-	if diffused && lights > 0 {
+	if lights := s.scene.Lights(); diffused && lights > 0 {
 		direct, coverage := s.traceDirect(lights, point, normal, rnd)
 		energy = energy.Merged(direct.Strength(mat.Color), signal)
 		signal = signal.Amplified(1 - coverage)
@@ -98,9 +99,8 @@ func (s *sampler) traceDirect(num int, point geom.Vector3, normal geom.Direction
 	limit := int(math.Min(float64(s.direct), float64(num)))
 	for i := 0; i < limit; i++ {
 		light := s.scene.Light(rnd)
-		ray, solidAngle := light.Box().ShadowRay(point, rnd)
-		cos := ray.Dir.Cos(normal)
-		if cos <= 0 {
+		ray, solidAngle := light.Box().ShadowRay(point, normal, rnd)
+		if solidAngle <= 0 {
 			break
 		}
 		coverage += solidAngle
@@ -108,7 +108,7 @@ func (s *sampler) traceDirect(num int, point geom.Vector3, normal geom.Direction
 		if !hit.Ok {
 			break
 		}
-		e := hit.Surface.Material().Emit().Amplified(solidAngle * cos / math.Pi)
+		e := hit.Surface.Material().Emit().Amplified(solidAngle / math.Pi)
 		energy = energy.Plus(e)
 	}
 	return energy, coverage
diff --git a/scene.go b/scene.go
index f52e2ac..16070e2 100644
--- a/scene.go
+++ b/scene.go
@@ -48,7 +48,6 @@ func NewScene(surfaces ...surface.Surface) *Scene {
 func (s *Scene) Intersect(ray *geom.Ray3) surface.Hit {
 	atomic.AddUint64(&s.rays, 1)
 	return s.tree.Intersect(ray)
-	// return s.tree.IntersectSurfaces(ray, math.Inf(1))
 }
 
 // Rays returns the total count of Ray/Scene intersections tested since the Scene was created.
diff --git a/surface/box.go b/surface/box.go
index 3d918af..e305780 100644
--- a/surface/box.go
+++ b/surface/box.go
@@ -95,15 +95,15 @@ func (b *Box) Contains(p geom.Vector3) bool {
 // chooses a random point within that disc,
 // and returns a Ray3 from the origin to the random point.
 // https://marine.rutgers.edu/dmcs/ms552/2009/solidangle.pdf
-func (b *Box) ShadowRay(origin geom.Vector3, rnd *rand.Rand) (*geom.Ray3, float64) {
-	norm := origin.Minus(b.Center).Unit()
-	center2 := b.Center.Plus(norm.Scaled(-b.Radius))
-	x, y := geom.RandPointInCircle(b.Radius, rnd)
-	right := norm.Cross(geom.Up)
-	up := right.Cross(norm)
-	point := center2.Plus(right.Scaled(x)).Plus(up.Scaled(y))
+func (b *Box) ShadowRay(origin geom.Vector3, normal geom.Direction, rnd *rand.Rand) (*geom.Ray3, float64) {
+	forward := origin.Minus(b.Center).Unit()
+	x, y := geom.RandPointInCircle(b.Radius, rnd) // TODO: push center back along "forward" axis, away from origin
+	right := forward.Cross(geom.Up)
+	up := right.Cross(forward)
+	point := b.Center.Plus(right.Scaled(x)).Plus(up.Scaled(y))
 	ray := geom.NewRay(origin, point.Minus(origin).Unit()) // TODO: this should be a convenience method
-	dist := center2.Minus(origin).Len()
-	weight := (b.Radius * b.Radius) / (2 * dist * dist) // cosine-weighted ratio of disc surface area to hemisphere surface area
-	return ray, weight
+	dist := b.Center.Minus(origin).Len()
+	cos := ray.Dir.Cos(normal)
+	solidAngle := cos * (b.Radius * b.Radius) / (2 * dist * dist) // cosine-weighted ratio of disc surface area to hemisphere surface area
+	return ray, solidAngle
 }
diff --git a/surface/cube.go b/surface/cube.go
index 25dfe42..4f742db 100644
--- a/surface/cube.go
+++ b/surface/cube.go
@@ -32,9 +32,9 @@ func (c *Cube) transform(m *geom.Matrix4) *Cube {
 	c.Pos = c.Pos.Mult(m)
 	min := c.Pos.MultPoint(geom.Vector3{})
 	max := c.Pos.MultPoint(geom.Vector3{})
-	for x := -1.0; x <= 1; x += 2 {
-		for y := -1.0; y <= 1; y += 2 {
-			for z := -1.0; z <= 1; z += 2 {
+	for x := -0.5; x <= 0.5; x += 1 {
+		for y := -0.5; y <= 0.5; y += 1 {
+			for z := -0.5; z <= 0.5; z += 1 {
 				pt := c.Pos.MultPoint(geom.Vector3{x, y, z})
 				min = min.Min(pt)
 				max = max.Max(pt)
diff --git a/surface/sphere.go b/surface/sphere.go
index ef92e11..1f1fdd9 100644
--- a/surface/sphere.go
+++ b/surface/sphere.go
@@ -32,9 +32,9 @@ func (s *Sphere) transform(t *geom.Matrix4) *Sphere {
 	s.Pos = s.Pos.Mult(t)
 	min := s.Pos.MultPoint(geom.Vector3{})
 	max := s.Pos.MultPoint(geom.Vector3{})
-	for x := -1.0; x <= 1; x += 2 {
-		for y := -1.0; y <= 1; y += 2 {
-			for z := -1.0; z <= 1; z += 2 {
+	for x := -0.5; x <= 0.5; x += 1 {
+		for y := -0.5; y <= 0.5; y += 1 {
+			for z := -0.5; z <= 0.5; z += 1 {
 				pt := s.Pos.MultPoint(geom.Vector3{x, y, z})
 				min = min.Min(pt)
 				max = max.Max(pt)
@@ -71,6 +71,7 @@ func (s *Sphere) Box() *Box {
 
 // Intersect tests whether the sphere intersects a given ray.
 // http://tfpsly.free.fr/english/index.html?url=http://tfpsly.free.fr/english/3d/Raytracing.html
+// TODO: http://kylehalladay.com/blog/tutorial/math/2013/12/24/Ray-Sphere-Intersection.html
 func (s *Sphere) Intersect(ray *geom.Ray3) Hit {
 	if ok, _, _ := s.box.Check(ray); !ok {
 		return Miss