COLMAP Camera support

README.md

@@ -4,8 +4,9 @@ Structs for interacting with reconstruction data from different SFM programs
 
 ## COLMAP
 
-Interact with COLMAPS's `points3D.bin` file output under the sparse reconstruction data.
+### Point Data
 
+Interact with COLMAPS's `points3D.bin` file output under the sparse reconstruction data.
 
 ```golang
 package example
@@ -17,18 +18,40 @@ import (
 )
 
 func main() {
-	points, err := colmap.ReadPoints3D("ColmapProject/sparse/0/points3D.bin")
-
+	points, err := colmap.ReadPoints3DBinary("ColmapProject/sparse/0/points3D.bin")
 	if err != nil {
 		panic(err)
 	}
 
-
 	fmt.Printf("File contains %d points", len(points))
 }
 
 ```
 
+### Cameras
+
+Interact with COLMAPS's `cameras.bin` file output under the sparse reconstruction data.
+
+```golang
+package example
+
+import (
+	"fmt"
+
+	"github.com/EliCDavis/sfm/colmap"
+)
+
+func main() {
+	cameras, err := colmap.ReadCamerasBinary("ColmapProject/sparse/0/cameras.bin")
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("File contains %d cameras", len(cameras))
+}
+
+```
+
 ## Meshroom
 
 Interact with Meshroom's `cameras.sfm` file output from the `StructureFromMotion` step.
@@ -44,7 +67,6 @@ import (
 
 func main() {
 	cameras, err := meshroom.LoadCameras("MeshroomProject/MeshroomCache/StructureFromMotion/abc123/cameras.sfm")
-
 	if err != nil {
 		panic(err)
 	}
@@ -68,7 +90,6 @@ import (
 
 func main() {
 	reconstructions, err := opensfm.LoadReconstruction("MyOpenSFMProject/reconstruction.json")
-
 	if err != nil {
 		panic(err)
 	}

colmap/cameras.go

@@ -0,0 +1,103 @@
+package colmap
+
+import (
+	"encoding/binary"
+	"fmt"
+	"os"
+
+	"github.com/EliCDavis/bitlib"
+)
+
+type CameraModel int
+
+const (
+	SIMPLE_PINHOLE CameraModel = iota
+	PINHOLE
+	SIMPLE_RADIAL
+	RADIAL
+	OPENCV
+	OPENCV_FISHEYE
+	FULL_OPENCV
+	FOV
+	SIMPLE_RADIAL_FISHEYE
+	RADIAL_FISHEYE
+	THIN_PRISM_FISHEYE
+)
+
+func (cm CameraModel) NumParameters() int {
+	switch cm {
+	case SIMPLE_PINHOLE:
+		return 3
+
+	case PINHOLE:
+		return 4
+
+	case SIMPLE_RADIAL:
+		return 4
+
+	case RADIAL:
+		return 5
+
+	case OPENCV:
+		return 8
+
+	case OPENCV_FISHEYE:
+		return 8
+
+	case FULL_OPENCV:
+		return 12
+
+	case FOV:
+		return 5
+
+	case SIMPLE_RADIAL_FISHEYE:
+		return 4
+
+	case RADIAL_FISHEYE:
+		return 5
+
+	case THIN_PRISM_FISHEYE:
+		return 12
+	}
+	panic(fmt.Errorf("unimplemented Camera Model Parameter Count %d", cm))
+}
+
+type Camera struct {
+	ID     int
+	Model  CameraModel
+	Width  uint64
+	Height uint64
+	Params []float64
+}
+
+func ReadCamerasBinary(filename string) ([]Camera, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	reader := bitlib.NewReader(f, binary.LittleEndian)
+
+	numCameras := reader.UInt64()
+	cameras := make([]Camera, numCameras)
+
+	for i := uint64(0); i < numCameras; i++ {
+		c := Camera{}
+
+		c.ID = int(reader.Int32())
+		c.Model = CameraModel(reader.Int32())
+		c.Width = reader.UInt64()
+		c.Height = reader.UInt64()
+
+		paramCount := c.Model.NumParameters()
+		c.Params = make([]float64, paramCount)
+		for pI := 0; pI < paramCount; pI++ {
+			c.Params[pI] = reader.Float64()
+		}
+
+		cameras[i] = c
+	}
+
+	return cameras, reader.Error()
+}