Add common functions for loading calibration with some error checking

From Bernd

src/utils.cpp

@@ -0,0 +1,92 @@
+/*
+ * COPYRIGHT AND PERMISSION NOTICE
+ * Penn Software MSCKF_VIO
+ * Copyright (C) 2017 The Trustees of the University of Pennsylvania
+ * All rights reserved.
+ */
+
+#include <msckf_vio/utils.h>
+#include <vector>
+
+namespace msckf_vio {
+namespace utils {
+
+Eigen::Isometry3d getTransformEigen(const ros::NodeHandle &nh,
+                                    const std::string &field) {
+  Eigen::Isometry3d T;
+  cv::Mat c = getTransformCV(nh, field);
+
+  T.linear()(0, 0)   = c.at<double>(0, 0);
+  T.linear()(0, 1)   = c.at<double>(0, 1);
+  T.linear()(0, 2)   = c.at<double>(0, 2);
+  T.linear()(1, 0)   = c.at<double>(1, 0);
+  T.linear()(1, 1)   = c.at<double>(1, 1);
+  T.linear()(1, 2)   = c.at<double>(1, 2);
+  T.linear()(2, 0)   = c.at<double>(2, 0);
+  T.linear()(2, 1)   = c.at<double>(2, 1);
+  T.linear()(2, 2)   = c.at<double>(2, 2);
+  T.translation()(0) = c.at<double>(0, 3);
+  T.translation()(1) = c.at<double>(1, 3);
+  T.translation()(2) = c.at<double>(2, 3);
+  return T;
+}
+
+cv::Mat getTransformCV(const ros::NodeHandle &nh,
+                       const std::string &field) {
+  cv::Mat T;
+  try {
+    // first try reading kalibr format
+    T = getKalibrStyleTransform(nh, field);
+  } catch (std::runtime_error &e) {
+    // maybe it's the old style format?
+    ROS_DEBUG_STREAM("cannot read transform " << field
+                     << " in kalibr format, trying old one!");
+    try {
+      T = getVec16Transform(nh, field);
+    } catch (std::runtime_error &e) {
+      std::string msg = "cannot read transform " + field + " error: " + e.what();
+      ROS_ERROR_STREAM(msg);
+      throw std::runtime_error(msg);
+    }
+  }
+  return T;
+}
+
+cv::Mat getVec16Transform(const ros::NodeHandle &nh,
+                          const std::string &field) {
+  std::vector<double> v;
+  nh.getParam(field, v);
+  if (v.size() != 16) {
+    throw std::runtime_error("invalid vec16!");
+  }
+  cv::Mat T = cv::Mat(v).clone().reshape(1, 4); // one channel 4 rows
+  return T;
+}
+
+cv::Mat getKalibrStyleTransform(const ros::NodeHandle &nh,
+                                const std::string &field) {
+  cv::Mat T = cv::Mat::eye(4, 4, CV_64FC1);
+  XmlRpc::XmlRpcValue lines;
+  if (!nh.getParam(field, lines)) {
+    throw (std::runtime_error("cannot find transform " + field));
+  }
+  if (lines.size() != 4 || lines.getType() != XmlRpc::XmlRpcValue::TypeArray) {
+    throw (std::runtime_error("invalid transform " + field));
+  }
+  for (int i = 0; i < lines.size(); i++) {
+    if (lines.size() != 4 || lines.getType() != XmlRpc::XmlRpcValue::TypeArray) {
+      throw (std::runtime_error("bad line for transform " + field));
+    }
+    for (int j = 0; j < lines[i].size(); j++) {
+      if (lines[i][j].getType() != XmlRpc::XmlRpcValue::TypeDouble) {
+        throw (std::runtime_error("bad value for transform " + field));
+      } else {
+        T.at<double>(i,j) = static_cast<double>(lines[i][j]);
+      }
+    }
+  }
+  return T;
+}
+
+} // namespace utils
+} // namespace msckf_vio