added paper

README.md

@@ -4,14 +4,15 @@ This repository contains addon files for Scaramuzzas OcamCalib Toolbox.
 More information about the addon can be found in the paper.
 If you use the addons, consider citing it.
 
-  @article{urban2015improved,
-  title={Improved wide-angle, fisheye and omnidirectional camera calibration},
-  author={Urban, Steffen and Leitloff, Jens and Hinz, Stefan},
-  journal={ISPRS Journal of Photogrammetry and Remote Sensing},
-  volume={108},
-  pages={72--79},
-  year={2015},
-  publisher={Elsevier}}
+    @article{urban2015improved,
+      title={Improved wide-angle, fisheye and omnidirectional camera calibration},
+      author={Urban, Steffen and Leitloff, Jens and Hinz, Stefan},
+      journal={ISPRS Journal of Photogrammetry and Remote Sensing},
+      volume={108},
+      pages={72--79},
+      year={2015},
+      publisher={Elsevier}
+    }
 
 ## Installation instruction ##
 1. Download and extract the original toolbox Scaramuzza_OCamCalib_v3.0 from