# Direct Linear Transform (DLT)

DLT is a method to estimate the camera intrinsics and extrinsics. Learned from Cyrill Stachniss.

Resources

- Direct Linear Transform for Camera Calibration and Localization (Cyrill Stachniss)
- Slides here

- Short 5 minute explanation by Cyrill

First, be familiar with Camera Calibration.

How many points are needed?

Calibrated camera

- 6 unknowns ($R,X_{O}$)
- We need at least 3 points
- Problem solved by Spatial Resection

Uncalibrated camera

- 11 unknowns ($K,R,X_{O}$)
- We need at least 6 points
- Assuming the model of an affine camera
- Problem solved by DLT

### Solving for $P$

### Decomposition of $P$ into $K,R,X_{O}$

We need to do Matrix Decomposition, through QR decomposition.

### Related

- Spatial Resection for Calibrated Camera