Corners of building roofs are classified as hight vegetation. How to change that?

[Lucie Botta]

Dear all,

The corners of the roof buildings are wrongly classified as high vegetation. How can I remove the classification as vegetation  from my buildings and change the points that belong to the roof to building classification? 

Best regards
Lucie Botta

[Steeve Brissette]

Try using WIDE GUTTER

Steeve Brissette 

Civil/Geomatics Technician 

TDB Consultants Inc.

Cell: 250-649-9846

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[Tobias K Kohoutek]

Dear Lucie,

automatically you might have the chance to use lasheight and set the classification for points above a specific height to class 6. Of course here comes the difficulty that you might have also heigh trees. You've to check your data regarding tree height vs. building height. Otherwise there will be only manual labour to reclassify those points.

Cheers,

Tobias

[Martin Isenburg]

Hello,

the algorithm in LAStools is searching for and classifying planar roofs (not entire buildings). One approach to get more of the building classified would be to use the found roof points, create polygons from them, buffer the polygons by 50 cm or so in each direction and then classify all points falling into these buffered polygons while ignoring ground / noise / points above a certain height / etc ... also into the building class (or better first to a temporary other class) using lasclip. 

Regards,

Martin @rapidlasso

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[Ringle, Bill]

This would not help with peaked/pitched roofs, correct?

[Floris Groesz]

all solutions based on the classificatin og single points will have difficulties. Vectorization og the found building points and buffering is also not ideal in my opinion.
Using context is a better solution but as far as I know this is not possible with LAStools (yet).
The detection of planar surfaces is a good start. These planes should then be used as seeds in a region growing procedures. So instead of using a fixed buffer, the points on the building edges should be evaluated using several criteria.
This is possible in software like eCognition and other OBIA (object based image analysis) software.

Floris