You called :
./pool pool_2.jpg pool_1.jpg ground.yml
Using 4.89 as sensor width and 4.15mm as focal
Detecting CCTag markers in first image
Found 15 reliable markers
Detecting CCTag markers in second image
Found 15 reliable markers
Mached 15 markers; using them for reconstruction

Found an Essential matrix:
	precision: 0.203877 pixels
	#inliers: 15
	#matches: 15

Triangulation residuals statistics:
	-- Residual min:	1.13687e-13
	-- Residual median:	0.0221191
	-- Residual max:	 0.201383
	-- Residual mean:	 0.0492089

Bundle Adjustment statistics (approximated RMSE):
 #views: 2
 #poses: 2
 #intrinsics: 1
 #tracks: 12
 #residuals: 48
 Initial RMSE: 0.0551273
 Final RMSE: 0.0364877
 Time (s): 0.001127

|   18|   19|   1.75146|     131.3|   129.549|   98.6661%|
|   14|   17|   463.742|     159.5|   304.242|   190.747%|
|   15|   17|   331.425|     213.9|   117.525|   54.9437%|
|   16|   17|     327.4|     327.4|         0|         0%|
|   15|   16|   4.06447|     192.4|   188.336|   97.8875%|
|   14|   16|   393.382|     217.4|   175.982|   80.9487%|
OpenCV Error: Assertion failed ((M0.type() == 5 || M0.type() == 6) && M0.rows == 3 && M0.cols == 3) in warpPerspective, file /Users/dgeld/src/opencv-fork/modules/imgproc/src/imgwarp.cpp, line 3002
libc++abi.dylib: terminating with uncaught exception of type cv::Exception: /Users/dgeld/src/opencv-fork/modules/imgproc/src/imgwarp.cpp:3002: error: (-215) (M0.type() == 5 || M0.type() == 6) && M0.rows == 3 && M0.cols == 3 in function warpPerspective

Abort trap: 6