It might just be possible that background modelling of diffraction data in the presence of ice rings is better done in more modern software.

Paul.


On 06/03/2021 00:10, Edward A. Berry wrote:
(Obviously this is for culling the bad data after data reduction is complete- doesn't do anything to prevent the ice ring from introducing error in the scaling process. Not really what you were asking for, and maybe not even useful now, given automatic outlier rejection in today's programs)

On 03/05/2021 04:00 PM, Edward A. Berry wrote:
For manually masking out the rings, you can use mtz2various to dump reflections in resolution ranges without ice in ascii, cat them all together and use f2mtz to read them into a new mtz file. Example attached.

You might also be able to do it using mtzutils to write out mtz files in limited resolution ranges, and then to merge them back into one file.

On 03/04/2021 10:39 AM, Alexander Brown wrote:
Hi all,
I'm struggling with a dataset I have which shows very poor data quality around 3.6A, or exactly where I can see a significant ice ring in the images. I'm trying to use mosflm to process the image files, and I have seen a previous thread on the message board where it is recommended to turn on three tick boxes for ice ring exclusion, but despite this, as I continue through the processing sequence and use aimless, it still flags that the data is affected by an ice ring at that resolution, which you can also see in the quality/resolution graphs.

I have even tried making a mask in the moslfm viewer using the mask tool to cover the entire ice ring, but to no avail.

Finally I did have a go at using EVAL which is mentioned in the original post about ice rings, but it seems it depends on libgfortran3 packages which have now been replaced with libgfortran5 and so I didn't get very far.

Is there a manual way to mask out certain data, or could there be something with my data that is causing the automatic ice ring resolution not to be as effective?


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