# Contour Label and Area Calculation - U magnitude in ParaView

Hello,

I have got questions about labelling contours and calculating the area of a certain wind speed.

Question 1:
How can I label wind speed (U magnitude) at each contour?
e.g. 10.00, 9.98, 9.96, etc.

Question 2:
How can I calculate the area (m²) of a certain U magnitude in a dashed area?
e.g. If the dashed area is 500m², and if this dark orange colour represents 9.96 (U magnitude), I’d like to know how much area (m²) 9.96 U magnitude occurs in a dashed area (500m²).

Hello Mary,

Regarding question #1:
Is it possible to add labels to contour lines?
Example made based on that discussion (using Interactive Select Points On tool + Edit->Find Data):

Regarding question #2:
you could apply Countour filter with requested range of U magnitude values, then CellSize filter, and finally IntegrateVariables filter. In the Information panel you’ll see the area of interest. Example:

1.Model

2.Countour filter:

2A. Set range:

2B. View after filter applying:

3.CellSize filter - Area array (on Infromation tab):

4.IntegrateVafiables filter - Total area of region of interest (on Information tab):

You can also use Python Calculator filter for the last step.

Hope it helps.

Best Regards,
Pavel

Hi Pavel,

Thank you so much for your notes. It helps a lot!!

When tried, I have got some questions:

Question 3
Selecting the zone that I am interested in:

I used ‘Select Cells With Polygon’ to select the zone. However, it is not handy. I have to select the zone that is 1.3 multiplied by a building width. In order to do that, I manually counted the cell number.
Is there anyway that I can select the zone easily?

Question 4
Contour for U is missing:

I extracted the zone from Edit/ Find Data/ Extract Selection.

From the Extract Selection, I applied ‘contour filter’. Then, scrolled down for ‘contour By’. But there is no U magnitude. Only epsilon, k, nut, and p were shown. So, I could not get contour for U magnitude. How to get ‘contour By - U magnitude’?