Attempt loading sargans color over SRTM1 DEM

* Doesn't work, documented the limitation

Signed-off-by: Ryan Friedman <[email protected]>

README.md

@@ -54,3 +54,22 @@ ros2 launch grid_map_geo load_vrt_launch.xml
 
 **Note:** `grid_map_geo` uses asserts to catch coding errors; they are enabled by default when 
 building in debug mode, and removed from release mode.
+
+## Mixing data from different datums, resolutions, and raster sizes
+
+`grid_map_geo` does not yet support automatically overlaying color data over elevation data from 
+different sources. Currently, color data must be the same datum, resolution and size for both the 
+DEM raster and the color raster.
+
+As an example, `sertig_color.tif` color data can be requested loaded on the SRTM1 DEM at sertig:
+
+```bash
+ros2 launch grid_map_geo load_tif.launch.py params_file:=config/sargans_color_over_srtm1.yaml
+# OR 
+ros2 run --prefix 'gdb -ex run --args' grid_map_geo map_publisher --ros-args --params-file config/sargans_color_over_srtm1.yaml
+```
+
+These datasets are different sizes, different resultions, and use different datums.
+
+Either of these ways of launching cause a floating point crash in `grid_map::getIndexFromLinearIndex`. 
+This limitation may be addressed in a future version.

config/sargans_color_over_srtm1.yaml

@@ -0,0 +1,8 @@
+map_publisher:
+    ros__parameters:
+        gdal_dataset_path: /vsizip/vsicurl/https://terrain.ardupilot.org/SRTM1/N09E047.hgt.zip/N09E047.hgt
+        gdal_dataset_color_path: "resources/sargans_color.tif"
+        max_map_width: 3601
+        max_map_height: 3601
+        map_origin_latitude: 47.033333
+        map_origin_longitude: 9.433333

launch/load_tif.launch.py

@@ -4,7 +4,7 @@
 
 from launch import LaunchDescription
 from launch.actions import DeclareLaunchArgument
-from launch.conditions import IfCondition
+from launch.conditions import IfCondition, LaunchConfigurationEquals, LaunchConfigurationNotEquals
 from launch.substitutions import LaunchConfiguration
 
 from launch_ros.actions import Node
@@ -40,6 +40,19 @@ def generate_launch_description():
         ],
         output="screen",
         emulate_tty=True,
+        condition=LaunchConfigurationEquals(LaunchConfiguration("params_file"), "")
+    )
+
+    # map publisher node with params file
+    map_publisher_with_param_file = Node(
+        package="grid_map_geo",
+        namespace="grid_map_geo",
+        executable="map_publisher",
+        name="map_publisher",
+        parameters=[LaunchConfiguration("params_file")],
+        output="screen",
+        emulate_tty=True,
+        condition=LaunchConfigurationNotEquals(LaunchConfiguration("params_file"), "")
     )
 
     # rviz node
@@ -77,8 +90,22 @@ def generate_launch_description():
                 ),
                 description="Full path to the elevation texture file.",
             ),
+            DeclareLaunchArgument(
+                "gdal_dataset_color_path",
+                default_value=os.path.join(
+                    pkg_grid_map_geo, "resources", default_gdal_color_dataset
+                ),
+                description="Full path to the elevation texture file.",
+            ),
+            DeclareLaunchArgument(
+                "params_file",
+                default_value="",
+                description="YAML parameter file path.",
+            ),
+
             static_transform_publisher,
             map_publisher,
+            map_publisher_with_param_file,
             rviz,
         ]
     )