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QSM Output

Added by ARSENIOU GEORGIOS over 1 year ago

Hello,

I want to calculate some variables from the output file (i.e. detailed.csv) that results after the QSM implementation. First I would like to verify my understanding of the “segment_ID” and “parent_segment_ID” columns. I think that each row of the file is a cylinder, but a segment is a collection of several cylinders i.e. it is not just one cylinder essentially. Hence, the segment_ID or the parent_segment_ID consist from several cylinders. Please correct me if I am wrong. Furthermore, if I want to calculate the total length of each segment, can I sum the lengths (i.e. column length) of all cylinders included in the particular segment? Finally, what are the units of the values in the “length” column? Thank you in advance.

P.S. I am using the version Diabolo_Release_SimpleTree_Beta_4.33.06_Computree 5.0.054b

Cheers,
Georgios


Replies (1)

RE: QSM Output - Added by Hackenberg Jan over 1 year ago

Hi Georgios
yes you are right with one cylinder per row.
Several cylinders per segment belonging to each other is also right.
From my thesis:
4.5.1
Post processing
The first detected cylinder serves as the root of the tree model. For all other cylinders
the cylinder’s start point equals the end point of another cylinder. This fact enables the
storage of the cylinders in an efficient informatics tree structure. A cylinder, whose end
point equals the start point of a second cylinder, is considered to be the parent of this
second cylinder (and the second cylinder is named child of the first one).
Starting with the root cylinder, which is stored in the root node, an iterative search starts
to build the storage structure. For each processed cylinder all children are looked up. If
the cylinder has only one child, this child is stored in the same node. If a cylinder has
multiple children, for each child a new node connected to the parent node is generated.
If no children are found the tree structure ends in a leaf node. Multiple cylinders stored
in one node are called segments and are stored in an ordered list. As soon as a child
cylinder is added to the structure, it is processed like its parent, i.e. its children are
added to the structure as well.
A segment in the storage structure relates to the part of a branch between two neigh-
bouring branch junctions of the modelled tree.

yes you can sum up the length to get the length of a segment. the cylinders are also ordered from root to tips.

I think the unit is meters. Check pls. The cylinders should be at minimum 0.05m large. And often smaller 1.

My thesis can be found here and should be read:
https://www.researchgate.net/publication/318307721_SimpleTree_-_an_efficient_Open_Source_tool_to_estimate_Quantitative_Structural_Tree_Models_and_its_Statistical_Relevance

Jan

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