#3926: allow limit viewshed computation by angle
--------------------------+----------------------------------
Reporter: annakrat | Owner: grass-dev@…
Type: enhancement | Status: new
Priority: normal | Milestone: 8.0.0
Component: Raster | Version: unspecified
Resolution: | Keywords: r.viewshed, viewshed
CPU: All | Platform: All
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Comment (by annakrat):
For the record, this is my attempt with hardcoded values, which fails with
angle 1 to 270 (the viewshed is written but incorrect). Interestingly, it
works with angle 0 to 270.
{{{
index 95ecd47..94d0741 100644
--- a/raster/r.viewshed/eventlist.cpp
+++ b/raster/r.viewshed/eventlist.cpp
@@ -605,7 +605,20 @@ int is_point_outside_max_dist(Viewpoint vp,
GridHeader hd,
return 0;
}
+int is_point_inside_angle(Viewpoint vp,
+ dimensionType row, dimensionType col,
+ float minAngle, float maxAngle)
+{
+ double ang;
+
+ ang = atan2(vp.row -row, col - vp.col) * 180 / M_PI;
+ if (ang < 0)
+ ang += 360;
+ if (ang < minAngle || ang > maxAngle)
+ return 0;
+ return 1;
+}
/* ------------------------------------------------------------
//note: this is expensive because distance is not stored in the event
diff --git a/raster/r.viewshed/eventlist.h b/raster/r.viewshed/eventlist.h
index e071687..234e700 100644
--- a/raster/r.viewshed/eventlist.h
+++ b/raster/r.viewshed/eventlist.h
@@ -74,7 +74,9 @@ is_point_outside_max_dist(Viewpoint vp, GridHeader hd,
dimensionType row, dimensionType col,
float maxDist);
-
+int is_point_inside_angle(Viewpoint vp,
+ dimensionType row, dimensionType col,
+ float minAngle, float maxAngle);
/*sort the event list by the angle around the viewpoint) */
void sort_event_list(AMI_STREAM < AEvent > **eventList);
diff --git a/raster/r.viewshed/grass.cpp b/raster/r.viewshed/grass.cpp
index b9dac21..d5fa240 100644
--- a/raster/r.viewshed/grass.cpp
+++ b/raster/r.viewshed/grass.cpp
@@ -316,6 +316,11 @@ init_event_list_in_memory(AEvent * eventList, char
*rastName,
(*vp, *hd, i, j, viewOptions.maxDist))
continue;
+ if (!is_point_inside_angle(*vp, i, j, 1, 270)) {
+ add_result_to_inmem_visibilitygrid(visgrid, i, j,
+ hd->nodata_value);
+ continue;
+ }
/* if it got here it is not the viewpoint, not NODATA, and
within max distance from viewpoint; generate its 3 events
and insert them */
}}}
--
Ticket URL: <https://trac.osgeo.org/grass/ticket/3926#comment:1>
GRASS GIS <https://grass.osgeo.org>
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