View source for Wedge prism

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==General description==
The wedge prism is a small honed glass plate that is used to make an [[Bitterlich sampling|angle count sample]]. You can estimate [[basal area]] with [[Bitterlich_sampling#Choice_of_basal_area_factor|basal area factors]] of ½, 1, 2 or 4. Each prism has a constant factor.
The observer can do an [[Bitterlich sampling|angle count sample]] moving around the prism – while the prism is located at the sample point.

==Handling==
# Select the point for [[Bitterlich sampling|angle count sample]],
# Select starting point (tree) for the sample,
# Move around the prism in a 360° sweep and count the trees included in the sample till starting point is reached,
# Multiply the counted number with the respective [[Bitterlich_sampling#Choice_of_basal_area_factor|basal area factor]] of the prism (the result is an estimate of basal area in m² per ha)

<gallery widths=300px heights=300px>
file:Wedge-prism_IN.jpg‎|Tree is included in the sample
file:Wedge_prism02_OUT.jpg|Tree is not included in the sample
</gallery>
{| class="wikitable"
!Advantages
!Disadvantages
|-
|independence of power sources (no batteries needed)
|no digital storage of measurement results available.
|}

==Applications==
* [[Bitterlich sampling]]
* [[Bitterlich sampling|Angle count sample]]

==Related articles==
* [[Bitterlich sampling]]
 
[[category:Measurement devices]]