Opening .tiff geoimages consumes enormous memory

john_hobbyist

I want to open it and do some zooming with code I use. Also I want to read the coordinates from the image (I do not how, but I am searching it)

mrjj

@john_hobbyist
Ok then QImageReader is not the way as it can't access any coordinates.

I think you gave up on GDAL too fast. It's whats people seem to use.

john_hobbyist

@mrjj: yes with

gdalinfo

command on the terminal I get the information I want...
Is there any way to get these information from the terminal and feed it to my python code for further processing? In other words how do I read information posted in terminal and use it inside my python code?

Ok, I will try again gdal to open the .tif

mrjj

@john_hobbyist
Hi
well yes, you could call gdalinfo with QProcess
https://www.learnpyqt.com/tutorials/qprocess-external-programs/
read the section with "Getting data from the QProcess"

john_hobbyist

Hello,
Ok I read it.

What is wrong in this code, and I cannot run the command via python command:

import sys
import time

def flush_then_wait():
    sys.stdout.flush()
    sys.stderr.flush()
    time.sleep(0.5)

sys.stdout.write('gdalinfo UAV_image.tif')
flush_then_wait()

on the terminal I run gdalinfo UAV_image.tif and prints me the metadata of the .tif, but I cannot run it through the python script

mrjj

@john_hobbyist
hi
That code only prints the text to the console.
It does not try to run gdalinfo
The first part is just a test script to run that shows some output.

You want the part with
p = QProcess()
p.start("ffprobe", ['-show_format', '-show_streams', 'a.mp4.py'])

(replace the program and parameters)

also to read the result, you should also read the
"Getting data from the QProcess" part

You want to use the full Python program shown near teh end. it sets up reading from the process.

john_hobbyist

Ok, I understand the:

p = QProcess()
p.start("python", ["dummy_script.py"])

but not

p.start("ffprobe", ['-show_format', '-show_streams', 'a.mp4.py'])

I assume that I put "python" on "ffprobe" but what I put on '-show_format', '-show_streams' ??

Thanx

mrjj

@john_hobbyist
Hi
The first one, starts the python app with the parameter of a script name

This one
p.start("ffprobe", ['-show_format', '-show_streams', 'a.mp4.py'])

calls the app ffprobe with 4 parameters.

So you would do

p.start("gdalinfo ", ['UAV_image.tif'])

you might need a full path to the UAV_image.tif instead of just the name.

john_hobbyist

I have been stuck around two weeks on this. Maybe I should ask what I am trying to do, in order to help me, if somebody can, on this specific question.

So is there any sample code in QT so that I can open .tif files, show me the corner coordinates (I am trying to make it work with gdal)
and when zoom (by establishing 4 points on the .tif) in to show me the updated new corner coordinates?

I am trying this github code:
https://github.com/kklmn/OrthoView/blob/master/OrthoView.py
but I do not know how feasible it is

mrjj

@john_hobbyist
Hi
Well its not a trivial thing you want to do.
If you mean some meta data from the geotiff with "corner coordinates" then no.
Qt does not know the geotiff format and cannot read any META data from the file. (beside the actual tiff image)

if you can get that info from gdalinfo commandline, its not a bad idea.

Im not sure OrthoView.py will work for you as it seems to want to load all of the image and that seems to use
an excessive amount of ram.

Did you try something like
http://tuiview.org/
and see if that can even load the image ?

john_hobbyist

@mrjj said in Opening .tiff geoimages consumes enormous memory:

@john_hobbyist
Hi
Well its not a trivial thing you want to do.
If you mean some meta data from the geotiff with "corner coordinates" then no.
Qt does not know the geotiff format and cannot read any data from the file.

if you can get that info from gdalinfo commandline, its not a bad idea.

Im not sure OrthoView.py will work for you as it seems to want to load all of the image and that seems to use
an excessive amount of ram.

Did you try something like
http://tuiview.org/
and see if that can even load the image ?

Ok, I will take a look thank you! Can I add python code to the http://tuiview.org/ ?

Christian Ehrlicher

@mrjj said in Opening .tiff geoimages consumes enormous memory:

cannot read any data from the file.

It can read the image, but only completely which is obvious no meaningful way for big images. Therefore you have to use special libraries like e.g. gdal. So either you want to use geotiffs and have to learn what a georeferenced image is and how a geotiff is internally structured or don't use them.

mrjj

Ok, I will take a look thank you! Can I add python code to the http://tuiview.org/ ?

well its written in python witha bit of c code for the raster.
But it was more to see if that could load such a huge image.

john_hobbyist

I am reading the examples you have sent me, thank you! Also, I found this easy example (only one file): https://github.com/marcel-goldschen-ohm/MultiPageTIFFViewerPyQt/tree/master
but when running this:
https://github.com/marcel-goldschen-ohm/MultiPageTIFFViewerPyQt/blob/master/MultiPageTIFFViewerQt.py
I get this error, which I am trying to address:

Traceback (most recent call last):
  File "MultiPageTIFFViewerQt.py", line 15, in <module>
    from ImageViewerQt import ImageViewerQt
ModuleNotFoundError: No module named 'ImageViewerQt'

Any idea what this is? (I copied from the github and is wrong! What is this!)

mrjj

@john_hobbyist
Hi
It seems it uses https://github.com/marcel-goldschen-ohm/PyQtImageViewer
so you also download and install that

make sure you have all it lists
alt text

john_hobbyist

@mrjj said in Opening .tiff geoimages consumes enormous memory:

@john_hobbyist
Hi
It seems it uses https://github.com/marcel-goldschen-ohm/PyQtImageViewer
so you also download and install that

make sure you have all it lists

Ok, I have installed everything, but how I ask from https://github.com/marcel-goldschen-ohm/MultiPageTIFFViewerPyQt/blob/master/MultiPageTIFFViewerQt.py to "see" this: https://github.com/marcel-goldschen-ohm/PyQtImageViewer ??

I tried this kind:

import importlib
moduleName = input('Enter module name:')
importlib.import_module(moduleName)

from here: https://stackoverflow.com/questions/2349991/how-to-import-other-python-files
but it imports the python.py file, I am sure what it needs to import PyQtImageViewer anyway...! Any help would be appreciated. Thanks

mrjj

@john_hobbyist
Hi
Sadly i don't really know Python that well
I just thought you would have to save QtImageViewer.py to the project folder together with the other files
and it would be able to find it.
I am not sure how Python modules works / should be located.

But im pretty sure others will know :)

john_hobbyist

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