Update 'Shape-to-geotiff.md'

Shape-to-geotiff.md

@@ -1,4 +1,4 @@
-The VRAHerbicide task only processes tiff items as input.  
+## Transform a shape file to a tiff file
 If your input data is a processed shape file it first needs to be converted to geotiff, this can be done with the 'ShapeToGeoTiffTask'.  
 
 Pass the code of the shape item into the {code} parameter, this creates a new item with tiff data as a sibling of the shape item with the same parent 
@@ -22,4 +22,25 @@ POST /api/v1/items/{code}/tasks
 Response 400 Tasktype not found  
 Response 401 Not authenticated  
 Response 403 No WRITE permissions in item  
-Response 404 Item not found  
+Response 404 Item not found  
+
+##### Optional input parameters #####
+There are some optional task attribute input parameters for greater flexibility.
+
+* **inputLayers**  
+ * array of of input layer name strings
+* **algorithm**  
+ * Valid inputs can be found here https://gdal.org/programs/gdal_grid.html#interpolation-algorithms
+ * Example of the default **"invdistnn:radius=100:min_points=2"**
+* **resolution**
+ * The resolution in meters for the final tiff file. [1, 100]
+
+defaults are false
+
+```javascript
+{
+    "inputLayers": "[\"height\", \"lutum\"]", // the value is a string not a json array!
+    "algorithm": "invdistnn:radius=100:min_points=2",
+    "resolution": 5
+}
+```