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I am attempting to loop over dozen of https S3-hosted COPC (LAZ) files in Python for QGIS to (1) render them, and (2) write out a simple thumbnail Jpeg. Using the script below I can successfully loop over downloaded local COPC files, but I can't figure out how to load https S3-hosted COPC (LAZ) files into QGIS.

At line 16, next, QgsPointCloudLayer call either faults or crashes QGIS using an https address. (again this works with local files).

pLayer = QgsPointCloudLayer(urlLOLA, nameCOPC, "pdal", pLayerOptions)

Here is the full code block, but really figuring out how to load a COPC/LAZ file from an https address using QgsPointCloudLayer should the key. All the image writing is just extra here.

EDIT: updated code below to replace "pdal" with "copc" and added pause function to allow time for the streamed file to load and render.

from qgis.core import *
import time

def pause(seconds):
    print("Paused for " + str(seconds) + " seconds to allow load")
    time_end = time.time() + seconds
    while time.time() < time_end:
        QgsApplication.processEvents()

#S3 URL (now works also!)
files=["https://astrogeo-ard.s3-us-west-2.amazonaws.com/moon/lro/lola/LolaRDR_15N30N_270E285E.copc.laz",
       "https://astrogeo-ard.s3-us-west-2.amazonaws.com/moon/lro/lola/LolaRDR_15N30N_285E300E.copc.laz"]

#local files (works)
#files=["/tmp/LolaRDR_15N30N_270E285E.copc.laz",
#      "/tmp/LolaRDR_15N30N_285E300E.copc.laz"]

canvas = iface.mapCanvas()
for urlLOLA in files:
    nameCOPC=urlLOLA.split("/")[-1]
    nameJPEG="/tmp/" + nameCOPC.replace(".copc.laz","_thumb.jpg")

    pLayer = QgsPointCloudLayer(urlLOLA, nameCOPC, "copc")

    if pLayer.isValid():
        print(nameCOPC + ": " + str(pLayer.pointCount()))
        QgsProject.instance().addMapLayer(pLayer)

        #Grab newly added layer and set to 70% transparent
        layer = iface.activeLayer()
        layer.setOpacity(0.7)

        #zoom to layer and refresh
        extent = layer.extent()
        canvas.setExtent(extent)
        canvas.refresh()
        #force 60-second pause to allow streamed COPC to load and render
        pause(60)
        canvas.waitWhileRendering()

        #export Jpeg
        canvas.saveAsImage(nameJPEG,None,"JPEG")
        print("created file: " + nameJPEG)            
        
        #remove layer
        QgsProject.instance().removeMapLayer( layer.id() )
        canvas.refreshAllLayers()
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  • with the addition of the pause function, likely QgsApplication.processEvents(), there are some stability issues for QGIS. Not sure what is going on (memory leak?). In the end, I used downloaded local files, not streamed files.
    – Trent
    Sep 12 at 21:00

1 Answer 1

Reset to default
3

Change the provider from "pdal" to "copc"

With this code:

from qgis.core import *

#S3 URL
files=["https://astrogeo-ard.s3-us-west-2.amazonaws.com/moon/lro/lola/LolaRDR_15N30N_285E300E.copc.laz"]

canvas = iface.mapCanvas()
for urlLOLA in files:
    pLayer = QgsPointCloudLayer(urlLOLA, nameCOPC, "copc")

    if pLayer.isValid():
        QgsProject.instance().addMapLayer(pLayer)

Output:

enter image description here

enter image description here

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1
  • Brilliant - sure enough the update from from "pdal" to "copc" worked. Now since the COPC files are streamed, I had to add a delay into the script to allow the file to fully load and render before saving an image. Using canvas.waitWhileRendering() wasn't enough since the file still wasn't fully loaded. I added a "pause" timer function to the code above to help with that issue.
    – Trent
    Sep 9 at 17:55

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