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Pyramiden in ArcMap und ArcGIS Pro

Y_Chau

Ich habe einige 16-Bit-Drohnenbilder. Mir ist aufgefallen, dass die für diese Bilder in ArcMap generierten Pyramidendateien sechsmal kleiner sind als in ArcGIS Pro. Ich kann die ArcMap OVR-Dateien auch in Pro verwenden und es gibt keinen sichtbaren Unterschied in der Leistung. Haben Sie eine Idee, warum es einen so großen Unterschied in der Größe der Pyramidendateien geben könnte?

Mit freundlichen Grüßen

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Image management

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PeterBecker

I tool a look. This is a strange file. It appears to be drone imagery that was originally 8bit and has been exported as a 12bit JPEG compressed image with 256 being defined as NoData and set using JPEG12bit compression . It is not clear to me if this the original image rotated or export from an orthorectification process. Such processing creates artifacts at the edges. (In the following I set NoData to organize to highlight the issue)

JPEG has an issue in that traditionally it does not have NoData. The software that produced the image (could have been ArcMap) set NoData as 256. Please check this and set to 255 instead which would keep it in the 8bit range and compress much better. You will still see the JPEG artifacts. There are different ways to handle the masking of 8bit JPEG but it depends on how the image was exported.

The 12bit version of JPEG is not natively supported in ArcGIS Pro hence it is converting to 16bit and using Deflate (lossless) compression hence the increase in size. There is a relatively complex work around using GLAD that can be done, but I recommend checking first on the source of how the images were created.

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PeterBecker

Strange. Could be related to the skipping a level (eg skip level1) or a different compression. Can you send a sample file that you have from ArcMap and will take a look. Yes, the pyramids created in ArcMap should work fine in ArcGIS Pro.

Y_Chau

Hi @PeterBecker I sent you a sample image via private message. Hope to hear from you why Pro is using much larger pyramid files than ArcMap.

Sincerely

PeterBecker

Y_Chau

Hi @PeterBecker thanks for the advice. Once I corrected the bit depth by setting NoData to 255 instead of 256 the image pyramids were almost the same size in both apps.

The source images are 10 times the size and are 16 bit 4-band tiffs. These came from some drone processing software. I can send one to you if you want.

I used the Make Raster Layer tool to remove the 4th band and then Copy Raster to change to 8 bit. And I used JPEG compression at 75%. Can you suggest another compression that can reduce the size and also handle NoData artifacts in a better manner?

Sincerely

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