FAQ (Heat Overlay)
Regarding the 3 foliage options (BGT, Area, Geotiff)
From option 1: How I can adjust functions per tree, and is it possible to include the trees in the analysis, and not to filter them from the data just like buildings.
Simply open the Function Table, which can be accessed through the Building Popup in the ribbon bar. By default this table does not yet show the trees, since you have not yet adjusted them. Add the functions you would like to adjust and optionally filter on environmental attributes to show the relevant Heat-2019 Overlay attributes: Crown Factor, Bowen Ratio and Vegetation Fraction.
From option 2: I want to know exactly which data is expected, since the point data that I have does not seem to work.
What is expected for this step:
- Each geometry should be an area describing exactly the foliage of the tree, not the tree trunks. This allows users to define more precisely where the foliage is situated.
- Each area should contain a value indicating the height at which the foliage is situated. This height should be relative to the terrain height.
If you have a file that only contain tree locations as points, you should instead import these points as tree buildings and not import them as foliage areas. The imported trees will then use their height and their function's (or if supplied: building's) CROWN FACTOR to determine the foliage area.
For option 3, I would also like to know what this data should look like. For example, is this a grid with height values, where there are only trees? So no individual trees need to be identified?
The grid data provided should present, per cell, the height of the foliage relative to the terrain height. A foliage height of 0 or lower is handled as no data and therefor ignored.
We now have a point data set in which each tree is known as a loose point, to which the tree height and crown surface parameters are given at this time. How can I currently see the crown areas, which are calculated in m2, compared to the tree crown factor?
From the sentence "Tree height multiplied by" tree crown factor "judge wheter the surrounding cells are in the shade." I cannot figure out what exactly you calculate with this. Is this the crown diameter / cross section, radius, perimeter, area?
Does the tree then have 1 fixed height value, or does it calculate in the case of a geotiff with several height values to calculate a kind of sphere shape?
Do you start from a surface file (I see that the few BGT trees are currently defined together as a polygon)?
What exactly do you mean by foliage? Is that the height of the trees relative to the ground level?
What exactly does the foliage crown factor mean? What is calculated with that? I assume the crown diameter?
How are trees currently included in the model?
What is the effect of 1 tree compared to a group of trees (or forest) in the model? Is a distinction made in this?
Is it possible to add your own tree file to the module?
What should this file look like?
I now have a point file for all trees in a test area, with a tree height (m) and a crown area (m2) for each tree. Can I also use the height and crown area from my file in the model? I have tried a few things but it seems that you assume that there is a fixed foliage crown factor for every tree, so that is the same for every tree? I would therefore like to use my own calculated crowns, because a fixed factor is out of the question. Is that possible?