View source for Point sampling on raster

= First phase: systematic sampling =
# Click {{mitem|text=Plugins --> Manage and Install Plugins}}.
# Type in the search bar {{typed|text=Point sampling tool}}, click on the plugin name and then on {{button|text=Install plugin}}.
# Load the single band raster file ''C_ID.tif'' created by [[Convert vector to Raster]].
# Load the regular grid as vector point file ''systematic_grid100.shp''' created by [[Creating regular grid]].
# Make sure that both layers are ticked in the [TOC].
# Open the '''Point Sampling Tool''' clicking [[File:Qgis_psample_button.png]].
# Select the layer containing sampling points.
# Specify the output of the resulting vector file marking column with '''CTR + left click'''.
# Enter an output shapefile name ''systematic_grid100_cid.shp'' and path by clicking {{button|text=Browse}}.
# Confirm with {{button|text=OK}}. The new layer is added to the Layer Panel .
[[File:Qgis_point_sample.png|400px]]

= Second phase: stratified sampling with equal allocation =
* In the search engine of the Processing Toolbox, type Random selection and select '''Random selection within subsets''' under Vector selection tools of QGIS.
* Select the regular point grid (result of [[Creating regular grid]]) as the input layer.
* Select the Column name containing the grouping class code as ID field.
* Enter 10 as sample size for each category.
* Click {{button|text=Run}} to execute the algorithm.
* Mark the the regular point grid in the [[TOC]]. Right click, {{button|text=Save as...}}.
* Format of the output vector file is '''ESRI Shapefile'''
* Do not forget to tick '''Save only selected features'''. 
* Define directory and output file name.
* Click {{button|text=Run}} to save the file.
[[File:Qgis_vector_saveas2.png|400px]]
[[category:Working with Vector Data]]