Add doc for Pleiades ortho products

docs/examples/pleiades.rst

@@ -4,8 +4,8 @@ Pleiades
 --------
 
 ASP supports the 1A/1B and NEO satellites from Airbus Pleiades. For NEO, see
-:numref:`pleiades_neo` for additional notes. ASP works only with primary
-(non-ortho) images.
+:numref:`pleiades_neo` for additional notes. ASP also supports the Pleiades ortho
+products, if the projection was done on a surface of constant height  (:numref:`pleiades_projected`).
 
 The Airbus Pleiades data have both an exact linescan camera model and an
 approximate RPC model (:numref:`rpc`). These are stored in separate files. The
@@ -122,6 +122,26 @@ Several peculiarities make the Pleiades NEO data different from 1A/1B (:numref:`
 - There is no field for standard deviation of the ground locations of pixels projected from the cameras, so error propagation is not possible unless such a value is specified manually (:numref:`error_propagation`).
 - The RPC camera models for a stereo triplet can be rather inconsistent with each other, resulting in large triangulation error. It is suggested to use instead the exact linescan camera model.
 
+.. _pleiades_projected:
+
+Pleiades projected images
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Airbus offers Pleiades ortho images, that are projected onto a surface of constant
+height above a datum. These products contain the string ``PRJ`` in the image and
+camera names, and have the ``PHR_PROJECTED`` keyword in the XML camera files.
+
+The projection height is stored in the ``DIM*PRJ*.XML`` camera model files,
+in the ``Bounding_Polygon`` field, in the ``<H>`` tag. This height is in meters,
+above the WGS84 ellipsoid.
+
+To process such data with ASP, use the provided RPC camera models, while passing
+the heights for the left and right images as part of the ``--ortho-height`` option,
+together with the option ``-t rpc``. See :numref:`mapproj_ortho` for details.
+
+ASP does not support Airbus images that are orthorectified with a 3D terrain
+model, as that terrain model is not known.
+
 .. _airbus_tiled:
 
 Pleiades tiled images

docs/next_steps.rst

@@ -877,10 +877,11 @@ An example without mapprojected images is shown in :numref:`bathy_reuse_run`.
 Stereo with ortho-ready images
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Some vendors offer images that have been mapprojected onto surfaces 
-of constant height above a datum. An example is Maxar's OR2A product.
+Some vendors offer images that have been projected onto surfaces 
+of constant height above a datum. Examples are Maxar's OR2A product
+and the Airbus Pleiades ortho product (:numref:`pleiades_projected`).
 
-The stereo command for such images is::
+The stereo command for Maxar (DigitalGlobe) data is::
 
     parallel_stereo                  \
       -t dg                          \
@@ -890,12 +891,14 @@ The stereo command for such images is::
       left.xml right.xml             \
       run/run
 
-Here, the values passed in via ``--ortho-heights`` are the heights above the
+The values passed in via ``--ortho-heights`` are the heights above the
 datum that were used to mapproject the images. The datum is read from the
 geoheader of the images.
 
-DEMs with such heights are created in the output directory, then the usual
-workflow of stereo with mapprojected images takes place.
+For Pleiades data and RPC cameras use instead ``-t rpc``.
+
+Helper DEMs with such heights are created in the output directory, then the
+usual workflow of stereo with mapprojected images takes place.
 
 .. _diagnosing_problems:
 

src/asp/Sessions/StereoSession.cc

@@ -225,17 +225,9 @@ namespace asp {
                                         vw::CamPtr & left_map_proj_cam, 
                                         vw::CamPtr & right_map_proj_cam) {
 
-    // Load the name of the camera model, session, and DEM used in mapprojection
-    // based on the record in that image. Load the bundle adjust prefix from the
-    // mapprojected image. It can be empty, when such a prefix was not used in
-    // mapprojection. 
     std::string l_adj_prefix, r_adj_prefix, l_image_file, r_image_file,
     l_cam_type, r_cam_type, l_cam_file, r_cam_file, l_dem_file, r_dem_file;
-    read_mapproj_header(left_image_file, left_camera_file, input_dem, session_name,
-                        l_adj_prefix, l_image_file, l_cam_type, l_cam_file, l_dem_file);
-    read_mapproj_header(right_image_file, right_camera_file, input_dem, session_name,
-                        r_adj_prefix, r_image_file, r_cam_type, r_cam_file, r_dem_file);
-
+
     vw::Vector2 heights = asp::stereo_settings().ortho_heights;
     bool have_heights = (!std::isnan(heights[0]) && !std::isnan(heights[1]));
     if (have_heights) {
@@ -246,6 +238,15 @@ namespace asp {
       if (l_adj_prefix != "" || r_adj_prefix != "")
         vw_throw(ArgumentErr() << "StereoSession: Expect no bundle adjustment prefix "
                  << "in ortho images geoheaders.\n");
+    } else {
+      // Load the name of the camera model, session, and DEM used in mapprojection
+      // based on the record in that image. Load the bundle adjust prefix from the
+      // mapprojected image. It can be empty, when such a prefix was not used in
+      // mapprojection. 
+      read_mapproj_header(left_image_file, left_camera_file, input_dem, session_name,
+                          l_adj_prefix, l_image_file, l_cam_type, l_cam_file, l_dem_file);
+      read_mapproj_header(right_image_file, right_camera_file, input_dem, session_name,
+                          r_adj_prefix, r_image_file, r_cam_type, r_cam_file, r_dem_file);
     }
 
     vw_out() << "Mapprojected images bundle adjustment prefixes: "