Pirâmides no ArcMap e ArcGIS Pro

Y_Chau

Eu tenho algumas imagens de drone de 16 bits. Observei que os arquivos de pirâmide gerados para essas imagens no ArcMap são 6 vezes menores do que no ArcGIS Pro. Eu também posso usar os arquivos OVR do ArcMap no Pro e não há diferença visível no desempenho. Alguma ideia de por que haveria uma diferença tão grande no tamanho dos arquivos de pirâmide?

Atenciosamente

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.