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Author Topic: Export of contours linked with NDVI data (for GIS analysis)  (Read 7648 times)

Alexey Pasumansky

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #15 on: February 22, 2017, 01:32:23 PM »
Ok, thank you, downloading it now.
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Alexey Pasumansky,
Agisoft LLC

SvaneSDU

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #16 on: February 22, 2017, 05:05:39 PM »
Out aim is to perform biological analyses of nature areas (thus not a farming application), flying in low altitude with a micasense red edge sensor.
To make stitched georeferenced maps in both large scale (landscape scale, high alt) and local scale (5x5 m og 20 x 20 m low alt) would be the optimal procedure for us. Thus having processed polygons of certain ndvi values will be nice to have.

Alexey Pasumansky

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #17 on: February 22, 2017, 08:02:13 PM »
Hello Niels,

We've checked the provided transformed ortho, and it seems that disabled color interpolation option confuses you.

For example, without interpolation you have dark green color for the index values approximately in the following interval [-0.08, 0.32] and everything above 0.32 is black, so using 0.1 step will cut off all values above 0.3 and you'll see that both dark green and black areas are in the same polygon.

So I mean that the palette step doesn't correspond to the contour lines steps and is not very detailed when interpolation is switched off. If you turn the interpolation on, you'll see the index representation in more detailed way.
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Alexey Pasumansky,
Agisoft LLC

SvaneSDU

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #18 on: February 24, 2017, 02:27:47 PM »
That makes sense, thank you.

Now the only thing that irritates me is that trees that should have a higher NDVI reading are shown as below -0.5. But when I dont know the precise origin of the image dataset, its doesn't matter.

Thanks again and have a nice weekend.

Niels

SvaneSDU

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #19 on: February 24, 2017, 02:43:19 PM »
Oh one more question:
Is there a way to generate all contours as close polygons? I loose a fair bit of data because the shapes aren't closed but represented as polylines. Can this be done by limiting the bounding box maybe?

Alexey Pasumansky

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #20 on: February 24, 2017, 02:49:18 PM »
Hello Niels,

How do you want to close the polylines? If you wish just to connect the first and the last vertices of the open polylines, it can be done using Python.
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Alexey Pasumansky,
Agisoft LLC

SvaneSDU

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #21 on: February 24, 2017, 03:14:26 PM »
It can also be don't in the postprocess in our GIS software (mapinfo), thus creating polygons from the polylines. Then afterwards the different polygons needs to be split because of overlays.

It would be a nice touch if a sort of outer limit/bounding box tool was included in the contour processing step.

Sudhir Payare

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #22 on: January 10, 2019, 01:49:48 PM »
How to export NDVI values through Agisoft?

Dave Martin

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Re: Export of contours linked with NDVI data (for GIS analysis)
« Reply #23 on: January 18, 2019, 02:58:12 PM »
Sudhir,

NDVI preparation and export is described in quite good detail in the manual. NDVI export is on page 43 of the current manual.

Dave