set options for thresholds and add description to html

grass-gis-addons/m.analyse.buildings/r.extract.buildings/r.extract.buildings.html

@@ -16,7 +16,8 @@ <h2>DESCRIPTION</h2>
 the <b>ndvi_perc</b> option) of NDVI values from all vegetated areas.
 Vegetated areas are defined from the FNK-vector - therefore the class
 codes have to be consistent. Alternatively, the NDVI threshold can be
-defined as a fixed NDVI value (on a scale from 0-255).
+defined as a fixed NDVI value (on a scale from 0-255). For this alternative the
+parameter <b>used_thresh</b> has to be set to <b>ndvi_thres</b>.
 <p>
 Only buildings with a defined minimum size and minimum height are
 extracted. The average story height is assumed to be 3 meters.

grass-gis-addons/m.analyse.buildings/r.extract.buildings/r.extract.buildings.py

@@ -80,7 +80,7 @@
 # % multiple: no
 # % label: Set if the percentile or the threshold of the NDVI should be used: ndvi_thresh or ndvi_perc
 # % options: ndvi_thresh,ndvi_perc
-# % answer: ndvi_thresh
+# % answer: ndvi_perc
 # % guisection: Parameters
 # %end
 
@@ -90,6 +90,7 @@
 # % required: no
 # % multiple: no
 # % label: Fix NDVI threshold (on a scale from 0-255) instead of estimated value from ndvi_perc and FNK
+# % options: 0-255
 # % answer: 145
 # % guisection: Parameters
 # %end
@@ -100,6 +101,7 @@
 # % required: no
 # % multiple: no
 # % label: NDVI percentile in vegetated areas to use for thresholding
+# % options: 0-100
 # % answer: 5
 # % guisection: Parameters
 # %end

grass-gis-addons/m.analyse.buildings/r.extract.greenroofs/r.extract.greenroofs.html

@@ -23,7 +23,8 @@ <h2>DESCRIPTION</h2>
 Empirical testing showed good results for a value of around
 <em>gb_thresh=145</em> (on a scale from 0 to 255). The threshold can
 also be automatically estimated from green areas defined in the FNK.
-For this, the <em>fnk</em>, <em>fnk_column</em>, and <em>gb_perc</em>
+For this, the parameter <b>used_thresh</b> must be set to <b>gb_perc</b> and
+the <em>fnk</em>, <em>fnk_column</em>, and <em>gb_perc</em>
 parameters must be given. The latter defines the percentile of pixels
 in vegetated areas to define as gleen-blue ratio threshold. Empirical
 testing yielded good results for <em>gb_perc=25</em> (=1st quartile).

grass-gis-addons/m.analyse.buildings/r.extract.greenroofs/r.extract.greenroofs.py

@@ -105,6 +105,7 @@
 # % required: no
 # % multiple: no
 # % label: Fix Green-Blue-Ratio threshold (on a scale from 0-255)
+# % options: 0-255
 # % answer: 145
 # % guisection: Parameters
 # %end
@@ -115,6 +116,7 @@
 # % required: no
 # % multiple: no
 # % label: Green-Blue-Ratio percentile in green areas to use for thresholding
+# % options: 0-100
 # % answer: 25
 # % guisection: Parameters
 # %end