[Qgis-user] Record the cracks in our (private) streets

[Charlotte Toma]

Hi Doug,

you can create photogrammetric export models (e.g. DEM, point cloud) 
with the open source software OpenDroneMap. Try WebODM [1] with the 
graphical user interface - you can install it with docker. The DEM is 
perfect for QGIS, you can create a 3D view of your Street with the 3d 
map view in QGIS and calculate the volume of the cracks.

Furthermore you can compare your pointclouds with the open source 
software CloudCompare [2] (Function "Cloud to Cloud Distance (C2C)") - 
with this function you can determine the change between two models (your 
two flights).

[1] https://www.opendronemap.org/webodm/
[2] https://www.danielgm.net/cc/


Greetings Charly

Charlotte Toma
GIS-Consultant
WhereGroup GmbH
Eifelstraße 7
53119 Bonn
Germany

Fon: +49 (0)228 / 90 90 38 - 24
Fax: +49 (0)228 / 90 90 38 - 11

info at wheregroup.com
www.wheregroup.com
Geschäftsführer:
Olaf Knopp, Peter Stamm
Amtsgericht Bonn, HRB 9885




>>> Am 14.12.2019 um 07:05 schrieb Doug <dougf.ccn at comcast.net>:
>> 
>>> 
>>> 
>>> I have imported a set of drone pictures to QGIS. They show the
>>> streets in my subdivision. I want to “record” the cracks in
>>> the pavement to be able to compare  them over time. I want to be
>>> able to segment the streets in arbitrary lengths. For each
>>> segment, I want to “draw” the cracks (in layers) to record
>>> where they are. Every year or two I will repeat the process. The
>>> purpose is to be able to compare the set of cracks in successive
>>> snapshots to see how the asphalt is holding up and identify
>>> underlying problems. I would love to have some software to find
>>> the cracks for me and generate the crack layer, if anyone knows of
>>> such software.
>>> 
>>> First problem: I can trace the outline of the streets to generate
>>> a layer which represents to road surface. Is there a way to slice
>>> that layer by picking two points to “slice” the layer and then
>>> have two layers? And then repeat the process so that I get the
>>> segments that I want? Alternatively, is there a way to create a
>>> segment and “snap” to next segment so there is not overlap or
>>> missing space?
>>> 
>>> Second problem. Given that I have a layer representing a segment
>>> of the road surface, can I “draw” the cracks for that segment
>>> such that every line in the cracks layer is related (as in SQL) to
>>> the segment it reside in?
>>> 
>>> Once I have the road surface segments, and the associated cracks,
>>> I can then use SQL to generate all sorts of reports on the cracks:
>>> average and median length, number of horizontal and vertical
>>> cracks, total crack length per road surface segment (or square
>>> feet), etc.
>>> 
>>> Thanks.
>>> 
>>> Doug
>>> 
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