diff --git a/src/site/markdown/index.md b/src/site/markdown/index.md
index e4b0bfbaa133fe3bbe8b237d9e5b8e91675b40e5..714311c95950097fc5bcce995031c7eaa6a8eafc 100644
--- a/src/site/markdown/index.md
+++ b/src/site/markdown/index.md
@@ -15,10 +15,12 @@
Overview
========
- Rugged is an add-on for Orekit handling Digital Elevation Models
+ Rugged is an add-on for Orekit handling Digital Elevation Models (DEM)
contribution to line of sight computation. It is a free software
intermediate-level library written in Java.
+ 
+
It mainly provides direct and inverse location, i.e. it allows
to compute accurately which ground point is looked at from a specific
pixel in a spacecraft instrument, and conversely which pixel will
@@ -28,6 +30,9 @@ Overview
on-board sensor pixels individual line-of-sights, spacecraft motion and
attitude and several physical effects.
+
+ *Effects of taking into account the DEM in the computation of latitude, longitude and altitude*
+
Direct and inverse location can be used to perform full ortho-rectification
of images and correlation between sensors observing the same area.
diff --git a/src/site/markdown/tutorials/direct-location-with-DEM.md b/src/site/markdown/tutorials/direct-location-with-DEM.md
index 8f6bc1f0ad7fce7f1da6e5f7a1d6cacc727b09b8..7cc291056b6f49be3b5c9fe610788dd3fb063e80 100644
--- a/src/site/markdown/tutorials/direct-location-with-DEM.md
+++ b/src/site/markdown/tutorials/direct-location-with-DEM.md
@@ -16,6 +16,9 @@
The aim of this tutorial is to compute a direct location grid by intersection of the line of sight with a DEM (Digital Elevation Model), using Duvenhage's algorithm. This algorithm is the most performant one in Rugged.
+The following figure shows the effects of taking into account the DEM in the computation of latitude, longitude and altitude:
+
+
## Feeding Rugged with DEM tiles
@@ -88,15 +91,16 @@ Here's the source code of the class `VolcanicConeElevationUpdater` :
* In Rugged terminology, the minimum latitude and longitude correspond to the centre of the farthest Southwest cell of the DEM. Be careful if using GDAL to pass the correct information as there is half a pixel shift with respect to the lower left corner coordinates in gdalinfo.
The following diagram illustrates proper DEM tiling with one line/column overlaps between neighbouring tiles :
-
+
+
This diagram tries to represent the meaning of the different parameters in the definition of a tile :
-
+
## Initializing Rugged with a DEM
-The initialization step differs slightly from the first tutorial [[DirectLocation|Direct location]], as we need to pass the information about our TileUpdater.
+The initialization step differs slightly from the first tutorial [Direct location](direct-location.html), as we need to pass the information about our TileUpdater.
Instantiate an object derived from TileUpdater :
@@ -116,7 +120,7 @@ Initialize Rugged with these parameters :
## Computing a direct location grid
-In a similar way as in the first tutorial [direct location](./direct-location.html), we call Rugged direct location method. This time it is called in a loop so as to generate a full grid on disk.
+In a similar way as in the first tutorial [[DirectLocation|Direct location]], we call Rugged direct location method. This time it is called in a loop so as to generate a full grid on disk.
DataOutputStream dos = new DataOutputStream(new FileOutputStream("demDirectLoc.c1"));
int lineStep = (maxLine - minLine) / nbLineStep;
diff --git a/src/site/markdown/tutorials/direct-location.md b/src/site/markdown/tutorials/direct-location.md
index 4253c9c5dc4bf5df1122d3f734828a2196615691..ca33ff4075618397744e5bf972ecc740cf7ac563 100644
--- a/src/site/markdown/tutorials/direct-location.md
+++ b/src/site/markdown/tutorials/direct-location.md
@@ -21,7 +21,7 @@ list of positions, velocities and attitude quaternions recorded during the acqui
passing all this information to Rugged, we will be able to precisely locate each point of
the image on the Earth. Well, not exactly precise, as this first tutorial does not use a
Digital Elevation Model, but considers the Earth as an ellipsoid. The DEM will be added in
-a second tutorial [Direct location with DEM](./direct-location-with-DEM.html). The objective here is limited to explain how to initialize everything
+a second tutorial [Direct location with DEM](direct-location-with-DEM.html). The objective here is limited to explain how to initialize everything
Rugged needs to know about the sensor and the acquisition.
@@ -215,6 +215,20 @@ On the fourth line, the arguments are the list of time-stamped positions and vel
for interpolation: number of points to use and type of filter for derivatives. The interpolation polynomials for nbPVPoints without any derivatives (case of CartesianDerivativesFilter.USE_P: only positions are used, without velocities) have a degree nbPVPoints - 1. In case of computation with velocities included (case of CartesianDerivativesFilter.USE_PV), the interpolation polynomials have a degree 2*nbPVPoints - 1. If the positions/velocities data are of good quality and spaced by a few seconds, one may choose only a few points but interpolate with both positions and velocities; in other cases, one may choose more points but interpolate only with positions.
We find the same arguments on the last line for the attitude quaternions.
+Rugged takes into account by default some corrections for more accurate locations:
+
+* light time correction (compensates or not light time between ground and spacecraft).
+* aberration of light correction (compensates or not aberration of light, which is velocity composition between light and spacecraft when the light from ground points reaches the sensor).
+
+Not compensating the delay or the velocity composition are mainly useful for validation purposes against system that do not compensate it. When the pixels line of sight already includes the aberration of light correction, one must obviously deactivate the correction.
+In order not to take into account those corrections, one must finalize Rugged initialization by setting the related flags to false:
+
+ rugged.setLightTimeCorrection(false);
+
+or
+
+ rugged.setAberrationOfLightCorrection(false);
+
The sensor models are added after initialization. We can add as many as we want.
@@ -223,12 +237,11 @@ The sensor models are added after initialization. We can add as many as we want.
## Direct location
Finally everything is set to do some real work. Let's try to locate a point on Earth
-
-Upper left point (first line, first pixel):
+for upper left point (first line, first pixel):
import org.orekit.bodies.GeodeticPoint;
Vector3D position = lineSensor.getPosition(); // This returns a zero vector since we set the relative position of the sensor w.r.T the satellite to 0.
- AbsoluteDate firstLineDate = lineSensor.getDate(1);
+ AbsoluteDate firstLineDate = lineSensor.getDate(0);
Vector3D los = lineSensor.getLos(firstLineDate, 0);
GeodeticPoint upLeftPoint = rugged.directLocation(firstLineDate, position, los);
diff --git a/src/site/markdown/tutorials/inverse-location.md b/src/site/markdown/tutorials/inverse-location.md
new file mode 100644
index 0000000000000000000000000000000000000000..275e87d5204694ef165e5c0b918532ac98dbc980
--- /dev/null
+++ b/src/site/markdown/tutorials/inverse-location.md
@@ -0,0 +1,54 @@
+<!--- Copyright 2013-2014 CS Systèmes d'Information
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
+# Inverse Location
+
+The aim of this tutorial is to compute the inverse location of a point on Earth in order to give the sensor pixel, with the associated line, seeing this point.
+
+We will also explain how to find the date at which sensor sees a ground point, which is a kind of inverse location only focusing on date.
+
+## Inverse location of a point on Earth
+The initialisation of Rugged is similar as in the [Direct location](direct-location.html) tutorial up to the addition of the lines sensor.
+
+### Point defined by its latitude, longitude and altitude
+Once Rugged initialised, one can compute the line number and the pixel number of a point defined by its Geodetic coordinates:
+
+ import org.orekit.bodies.GeodeticPoint;
+ import org.orekit.rugged.api.SensorPixel;
+ GeodeticPoint gp = new GeodeticPoint(latitude, longitude, altitude);
+ SensorPixel sensorPixel = rugged.inverseLocation(sensorName, gp, minLine, maxLine);
+where minLine (maxLine, respectively) is the minimum line number for the search interval (maximum line number, respectively).
+
+The inverse location will give the sensor pixel number and the associated line number seeing the point. In case the point cannot be seen between the prescribed line numbers, the return result is null. No exception will be thrown in this particular case.
+
+### Point defined by its latitude and longitude (no altitude)
+Similarly, one can compute the line number and the pixel number of a point defined solely by its latitude en longitude. The altitude will be determined automatically with the DEM.
+
+ SensorPixel sensorPixel = rugged.inverseLocation(sensorName, latitude, longitude, minLine, maxLine);
+
+## Date location
+Once Rugged initialised, one can compute the date at which sensor sees a point on Earth.
+
+### Point defined by its latitude, longitude and altitude
+For a point defined by its Geodetic coordinates:
+
+ AbsoluteDate dateLine = rugged.dateLocation(sensorName, gp, minLine, maxLine);
+
+### Point defined by its latitude and longitude (no altitude)
+Similarly, for a point defined solely by its latitude en longitude (altitude determined automatically with the DEM):
+
+ AbsoluteDate dateLine = rugged.dateLocation(sensorName, latitude, longitude, minLine, maxLine);
+
+## Source code
+The source code is available in InverseLocTutorial.java
diff --git a/src/site/markdown/tutorials/tile-updater.md b/src/site/markdown/tutorials/tile-updater.md
new file mode 100644
index 0000000000000000000000000000000000000000..9d1c398f105a9ed6e9ddbd8febb467aa29aaab3b
--- /dev/null
+++ b/src/site/markdown/tutorials/tile-updater.md
@@ -0,0 +1,14 @@
+<!--- Copyright 2013-2014 CS Systèmes d'Information
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+
diff --git a/src/site/resources/images/Earth_FlatVsRugged.gif b/src/site/resources/images/Earth_FlatVsRugged.gif
new file mode 100644
index 0000000000000000000000000000000000000000..5dc77587d908ab23012cbba2f79a52da1847a771
Binary files /dev/null and b/src/site/resources/images/Earth_FlatVsRugged.gif differ
diff --git a/src/site/resources/images/RuggedExplained.png b/src/site/resources/images/RuggedExplained.png
new file mode 100644
index 0000000000000000000000000000000000000000..a4afca93d0bc8478a7eab9b45fd839e8988b507c
Binary files /dev/null and b/src/site/resources/images/RuggedExplained.png differ
diff --git a/src/site/site.xml b/src/site/site.xml
index f3bf35b0785937b2a47266a9130c872c74e00e9c..6757d7cd08bafad01d59b3099c494ce8c34cbe0d 100644
--- a/src/site/site.xml
+++ b/src/site/site.xml
@@ -45,6 +45,8 @@
<menu name="Tutorials">
<item name="Direct location" href="/tutorials/direct-location.html" />
<item name="Direct location with DEM" href="/tutorials/direct-location-with-DEM.html" />
+ <item name="Inverse location" href="/tutorials/inverse-location.html" />
+ <item name="Tile Updater" href="/tutorials/tile-updater.html" />
</menu>
<menu name="Development">
<item name="Contributing" href="/contributing.html" />