Re: [Qgis-user] (no subject)

[Micha Silver via QGIS-User]

Hello Loke: We are working on a project in Date orchards. We also tried to create a point layer of tree crowns using drone acquired LIDAR. We created a Canopy Height Model, then used a local maxima procedure to identify crowns. It was a bit disappointing. It seems that dates, especially, have local peaks not at the tree center: Some of the central fronds extend outward from the tree center and they are the highest points. So we got more than one "crown" for each tree, and not really at the tree center. A better approach was to delineate the circumferences of each tree as polygons, from the CHM, and a minimum height above ground. Then we took the centroid of each polygon. That worked more or less OK on young orchards. But with older orchards, having a wide spread of fronds, and the canopy of one tree touching the next, this method also failed. So, not really a helpful suggestion, only possible pitfalls to look out for... Best, Micha    On 21/06/2023 11:10, Loke Jian Munn via QGIS-User wrote: Resend to include the attachment.   Thank you.   Loke Jian Munn Information Technology (IT) Department KUALA LUMPUR KEPONG BERHAD Wisma Taiko, No. 1, Jalan S.P. Seenivasagam, 30000 Ipoh,Perak Darul Ridzuan,Malaysia T    :  +605 240 8000 (ext. 2443)   From: Loke Jian Munn Sent: Wednesday, 21 June, 2023 4:09 PM To: kirk <k...@nortekresources.com>; qgis-user@lists.osgeo.org; Richard McDonnell <richard.mcdonn...@opw.ie> Subject: RE:   Hi,   As mention previously, I need NIR band to perform the NDVI, however my drone sensor does not record NIR band.   So, I trying another way which is crop counting from orthophoto with Python and Scikit Image. The whole process is geospatial as it works with raster and shapefiles and results are finally displayed on QGIS.   But the results I get are like below:     After Zoom in:   May I know what’s goes wrong ? I have attached the Python code above for references. For this project, I using an Orthomosaic layer with resolution of 5cm.   Appreciate if you can provide me some guidelines or insights in this as this is my first time touching python and scikit.   Thank you.   Regards, Loke Jian Munn Information Technology (IT) Department KUALA LUMPUR KEPONG BERHAD Wisma Taiko, No. 1, Jalan S.P. Seenivasagam, 30000 Ipoh,Perak Darul Ridzuan,Malaysia T    :  +605 240 8000 (ext. 2443)   From: kirk <k...@nortekresources.com> Sent: Tuesday, 6 June, 2023 6:09 PM To: Loke Jian Munn <jm.l...@klk.com.my>; qgis-user@lists.osgeo.org Subject:   Hi Loke   Richard suggested using a NDVI approach which would require data in the Near Infrared (NIR) band.  An orthomisaic would contain 3 colour bands, but not the NIR.  NDVI provides an understanding of plant greenness and health and may not be suitable for detecting oil palm's.     If you are getting 90 percent plus with your current approach , you may find that you will spend 4 times longer capturing the additional 10 percent.     NIR data,are available from various satellite sensors however, their resolution would not work at the individual plant level.   Some drone sensors record the NIR band.   Kirk Schmidt       Sent from my Galaxy   DISCLAIMER : This email and any attachments are confidential and intended solely for the addressee. If you are not the intended recipient, any disclosure, copying, distribution either whole or partial, is prohibited and may be unlawful. In such case, please delete this message and kindly notify the sender. Kuala Lumpur Kepong Berhad _______________________________________________ QGIS-User mailing list QGIS-User@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user -- Micha Silver Ben Gurion Univ. Sde Boker, Remote Sensing Lab cell: +972-523-665918

_______________________________________________
QGIS-User mailing list
QGIS-User@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user