added info about camera model

README.md

@@ -4,32 +4,16 @@ SVO
 Disclaimer
 ----------
 
-SVO has been tested under ROS Groovy and Hydro and Ubuntu 12.04 and 13.04. This is research code, expect that it changes often and any fitness for a particular purpose is disclaimed.
+SVO has been tested under ROS Groovy and Hydro and Ubuntu 12.04 and 13.04. This is research code, any fitness for a particular purpose is disclaimed.
 
 Installation Instructions
 -------------------------
 
-#### OPTIONAL: g2o - General Graph Optimization
+We use two workspaces, one for the plain CMake projects `Sophus`, `Fast` and optionally `g2o` and another workspace for the Catkin projects `rpg_vikit` and `rpg_svo`. Make sure to clone in the right folder.
-
-Only required if you want to run bundle adjustment. It is not necessary for visual odometry.
-g2o requires the following system dependencies: `cmake, libeigen3-dev, libsuitesparse-dev, libqt4-dev, qt4-qmake, libqglviewer-qt4-dev`, install them with `apt-get`
-    
-I suggest an out-of-source build of g2o:
-
-    cd workspace
-    git clone https://github.com/RainerKuemmerle/g2o.git
-    cd g2o
-    mkdir build
-    cd build
-    cmake ..
-    make
-    sudo make install
-
-If you don't want to make a system install, then you can replace the cmake command with `cmake .. -DCMAKE_INSTALL_PREFIX:PATH=$HOME/installdir` 
 
 #### Sophus - Lie groups
 
-Sophus by Hauke Strasdat implements Lie groups that we need to describe rigid body transformations.
+Sophus by Hauke Strasdat implements Lie groups that we need to describe rigid body transformations. Checkout in your workspace for plain CMake projects.
 
     cd workspace
     git clone https://github.com/strasdat/Sophus.git
@@ -55,6 +39,24 @@ To simplify installation we provide a CMake package that contains the fast detec
     cmake ..
     make
 
+#### OPTIONAL: g2o - General Graph Optimization
+
+Only required if you want to run bundle adjustment. It is not necessary for visual odometry. In fact, we don't run it on our MAVs.
+g2o requires the following system dependencies: `cmake, libeigen3-dev, libsuitesparse-dev, libqt4-dev, qt4-qmake, libqglviewer-qt4-dev`, install them with `apt-get`
+    
+I suggest an out-of-source build of g2o:
+
+    cd workspace
+    git clone https://github.com/RainerKuemmerle/g2o.git
+    cd g2o
+    mkdir build
+    cd build
+    cmake ..
+    make
+    sudo make install
+
+If you don't want to make a system install, then you can replace the cmake command with `cmake .. -DCMAKE_INSTALL_PREFIX:PATH=$HOME/installdir` 
+
 #### ViKit - Some useful tools that we need
 
 ViKit for instance contains camera models, some math and interpolation functions that SVO needs.
@@ -96,7 +98,7 @@ Now you are ready to start the rosbag. Open a new console and change to the dire
 
     rosbag play airground_rig_s3_2013-03-18_21-38-48.bag
     
-Now you should see the video with tracked features (green) and in RViz how the camera moves. 
+Now you should see the video with tracked features (green) and in RViz how the camera moves.
 
 SVO GUI
 -------
@@ -112,6 +114,17 @@ Make sure to active the console window when pressing the keys.
 * `q`   Quit
 * `r`   Reset
 
+Camera Calibration
+------------------
+
+You need a calibrated camera to run SVO. We use the Matrix Vision Bluefox cameras in our lab, which have VGA resolution and global shutter.
+SVO supports three camera models: 
+
+1. The `ATAN` model --- our preference --- which is also used by `PTAM`. This model uses the _FOV_ distortion model of "Deverneay and Faugeras, Straight lines have to be straight, 2001". You can calibrate your camera with this model by using the calibration tool in this package: https://github.com/ethz-asl/ethzasl_ptam We prefer this model because the projection and unprojection can be computed faster than with the other models. Further, the industral cameras that we use have neglectable tangential distortion.
+2. The `Pinhole` model with three radial and two tangential distortion parameters. This model is standard in OpenCV and ROS. You can use the ROS camera calibration tool: http://wiki.ros.org/camera_calibration
+3. The `Ocam` model by Davide Scaramuzza which can be used to model Omnidirectional cameras. Use the OCamCalib toolbox to calibrate your camera: http://rpg.ifi.uzh.ch/software_datasets.html
+Although SVO can be used with this camera model, the algorithm does not work yet (!) with omnidirectional cameras.
+
 Parameter Settings
 ------------------