A couple of bugfixes for sat_sim in special cases.

docs/tools/sat_sim.rst

@@ -440,7 +440,7 @@ is defined in :numref:`rig_config`.
 
 As an example, consider the setup from :numref:`sat_sim_roll_pitch_yaw`. Add the
 rig option, and do not set the image size, focal length, and optical center on
-the command line, as those are set by the rig. 
+the command line, as those are set by the rig configuration. 
 
 The produced image and camera file names will include the sensor name, before
 the image/camera extension. Example::
@@ -483,7 +483,7 @@ using the option ``--save-as-csm``.
    :name: sat_sim_rig_illustration
    :alt:  sat_sim_rig_illustration
 
-   Illustration of ``sat_sim`` creating a rig of 3 cameras. The resulting
+   Illustration of ``sat_sim`` creating a rig of 3 frame cameras. The resulting
    images have been mapprojected onto the ground.
 
 .. _sat_sim_time:
@@ -497,7 +497,7 @@ starting ground position (``--first-ground-pos``), and satellite velocity
 recorded for each acquisition.
 
 The time is measured in seconds in double precision. Time is important for
-pointing control with a rig.
+modeling a rig, when this option is set to true even when not explicitly set.
 
 The time will be saved with the linescan camera metadata. It will be part of the
 name of the pinhole cameras and images (but not part of the name for linescan
@@ -517,9 +517,9 @@ looks straight down at the starting point of the ground path. The default
 value is 10,000 seconds. 
 
 For different orbits it is suggested to use a different value for
-``--reference-time``. It is suggested to keep the reference time in the 10,000 -
-100,000 range to ensure the produced times are positive but not too large, which
-can result in loss of precision.
+``--reference-time``, and also a different output prefix. It is suggested to
+keep the reference time in the 1000 - 100,000 second range to ensure the produced
+and nearby times are positive but not too large, which can result in loss of precision.
 
 Here we also assumed a rig was present (:numref:`sat_sim_rig`), with the sensor
 name being ``haz_cam``.

src/asp/Camera/SatSim.cc

@@ -513,19 +513,30 @@ void adjustForFrameRate(SatSimOptions                  const& opt,
   // Number of cameras. Add 1 because we need to include the last camera.
   num_cameras = int(orbit_len / period) + 1;
 
+  // Cannot have one camera sample for linescan regardless of what the user wants
+  bool is_linescan = (opt.sensor_type.find("linescan") != std::string::npos);
+
   // Sanity checks. It is fine to have one single camera, but that is not usual.
   if (num_cameras < 1)
     vw::vw_throw(vw::ArgumentErr() << "The number of cameras must be at least 1.\n");
-  if (num_cameras == 1)
-    vw::vw_out(vw::WarningMessage) << "Warning: Creating only one camera sample.\n";
-
-  // Update the orbit length
-  orbit_len = period * (num_cameras - 1.0);
+  if (num_cameras == 1) {
+    if (is_linescan) {
+      vw::vw_out(vw::WarningMessage) << "For linescan cameras, must have at least "
+      "two camera samples. Adding a second one.\n";
+      num_cameras = 2;
+    } else {
+      vw::vw_out(vw::WarningMessage) << "Creating only one frame camera sample.\n";
+    }
+  }
 
+  // Update the orbit length. Handle gracefully the case of one camera.
+  orbit_len = period * std::max(num_cameras - 1.0, 1.0);
+
   // Sanity check, important for the work below. It is fine for first and last 
   // proj to be in the same location, but that is not usual.
   if (norm_2(last_proj - first_proj) < 1e-6)
-    vw::vw_out(vw::WarningMessage) << "Warning: The first and last camera positions are too close. Check your inputs.\n";
+    vw::vw_out(vw::WarningMessage) << "Warning: The first and last camera positions are "
+      <<"too close. Check your inputs.\n";
 
   // Travel along the orbit in very small increments. Return the last point
   // before exceeding the orbit length. 
@@ -562,8 +573,10 @@ void adjustForFrameRate(SatSimOptions                  const& opt,
 
   }
 
-  // Update the last orbit point, in projected coords
-  last_proj = out_proj;
+  // Update the last orbit point, in projected coords. Handle gracefully
+  // the case of one camera.
+  if (norm_2(last_proj - first_proj) > 1e-6)
+    last_proj = out_proj;
 }
 
 // Given the direction going from first_proj to last_proj, and knowing
@@ -871,6 +884,9 @@ void genCamPoses(SatSimOptions & opt,
   int last_pos = opt.num_cameras; // stop before last
   if (opt.sensor_type == "linescan") {
     // Double the number of cameras, half of extra ones going beyond image lines
+    if (opt.num_cameras < 2)
+      vw::vw_throw(vw::ArgumentErr() << "For linescan cameras, must have at least "
+        "two camera samples.\n");
     first_pos = -opt.num_cameras/2;
     last_pos  = 2 * opt.num_cameras + first_pos;
   }
@@ -1574,11 +1590,11 @@ void genRigCamerasImages(SatSimOptions          & opt,
     local_opt.optical_center[1] = params.GetOpticalOffset()[1];
     local_opt.image_size[0]     = params.GetDistortedSize()[0];
     local_opt.image_size[1]     = params.GetDistortedSize()[1];
-    local_opt.sensor_type       = sensor_types[sensor_it];
+    local_opt.sensor_type       = sensor_types[sensor_index];
 
     // The transform from the reference sensor to the current sensor
     Eigen::Affine3d ref2sensor = rig.ref_to_cam_trans[sensor_index];
-    std::string suffix = "-" + sensor_names[sensor_it]; 
+    std::string suffix = "-" + rig.cam_names[sensor_index];
     bool have_rig = true;
     genCamerasImages(ortho_nodata_val, have_rig, sensor_index, dem, height_guess, 
                      ortho_georef, ortho, local_opt, rig, dem_georef, suffix);