Changes between Version 4 and Version 5 of Grass7/TemporalGISAlgebra

Timestamp:

07/05/13 05:18:40 (12 years ago)

Author:

huhabla

Comment:

--

Grass7/TemporalGISAlgebra

@@ -1 +1 @@
 = Temporal GIS Algebra for Raster and Vector Data =
 
-Overview of the temporal algebra elements and concepts.
+== Introduction ==
+
+=== Temporal Algebra ===
+
+The idea of the temporal Algebra is to use operators that process space and time. 
+The spatial processing capabilities that are already implemented in GRASS GIS will be reused. 
+That are r.mapcalc for raster processing and v.buffer, v.over , v.patch for vector map processing. 
+Unfortunately the GRASS GIS temporal framework implements a separated time and space approach. 
+The only way to process several space time datasets in time is to use their temporal relationships, 
+since the time dimension has in our case an arbitrary layout.
+
+Here an example of the temporal Algebra that simply selects parts of a space time dataset without the processing raster or vector data:
+
+We define a selection operator ''':''' that by default selects parts of a space time dataset that are temporally equal to parts of a second, hence the following expression
+{{{
+C = A : B
+}}}
+means: Select all parts of space time dataset A that are equal to B and store it in space time dataset C. The parts are in this case time stamped maps. In addition we define the inverse selection operator '''!:''', hence the following expression
+
+C = A !: B
+
+means: select all parts of space time time dataset A that are not equal to B and store it in space time dataset (STDS) C.
+
+We defined the {topological relations, selection operator} operator to perform selection with 
+different temporal topology relations. Examples:
+
+{{{
+C = A {equals,:} B is exactly the same as C = A : B
+C = A {equals,!:} B is exactly the same as C = A !: B
+}}}
+
+We can now define arbitrary topological relations using logical or || to connect them:
+
+{{{
+C = A {equals||during||overlaps,:} B
+}}}
+
+Select all parts of A that are equal B, during B or overlaps B.
+
+In addition we define a temporal buffer function, that buffer time instances or time intervals:
+
+buff_t(STDS, "time interval")
+
+Example:
+
+{{{
+C = buff_t(A, "1 day")
+}}}
+
+Buffer all maps of STDS A with a temporal buffer of one day.
+
+= Overview of all temporal algebra elements =
 
 == Temporal topology relations ==
@@ -454 +505 @@
 possible in reference time mode.
 
-
-