Thank you for enlightening me and sorry for my ignorance, Peter.
On Sun, Apr 25, 2010 at 5:33 PM, Frank von Delft < [email protected]> wrote: > Hi, I sense a misunderstanding: > > Cell parameters are not relevant when scaling together datasets: what > matters are intensities and (depending on algorithm) directional cosines and > the like. > > Cell parameters are relevant, along with the other experimental parameters, > for knowing where to pick the intensities off the images ("integrating"). > What denzo & scalepack do (which I suspect you're referring to) is to split > this into separate actions: denzo integrates, and scalepack postrefines, > meaning it optimizes the integrated intensities by simultaneously taking > into account experimental parameters over whole dataset. Only then does it > scale. > > Xscale and Scala trust the intensities and only scale. > > Yes, the cell parameters are also an indicator that you may have > non-isomorphism, but only that; it's the *intensities* where this is > manifested. So you could have "different" cells yet still perfectly > isomorphous intensities; or "same" cells and terrible non-isomorphism. > > phx. > > > > > > On 25/04/2010 16:05, Peter Grey wrote: > > Dear Fred and Phil, > > However there is no refinement of these parameters in XSCALE so if you need > to scale together several crystals (e.g. very small crystals that show > severe radiation damage after a few degrees) you end up with a sub-optimal > combined dataset after XSCALE. I thought SCALA can take care of that and > define cell parameters that fit best all data as scalepack does when it > considers all separate frames , from all crystals where-as the input to > XSCALE is not separate frames but complete datasets). > > Peter. > > > On Sun, Apr 25, 2010 at 12:14 PM, Frederic VELLIEUX < > [email protected]> wrote: > >> Hi Phil, >> >> Indeed it does, both during integration (INTEGRATE, only if you "ask for >> it" with the proper keyword) and in the post-refinement step (CORRECT). >> Normally this should be quite sufficient. I haven't seen a single case where >> this was not sufficient. >> >> Fred. >> >> > Message du 25/04/10 09:55 >> > De : "Phil Evans" >> > A : [email protected] >> > Copie à : >> > Objet : Re: [ccp4bb] SUMMARY: scala and xds data >> >> > >> > >> > Just to point out that Scala does not refine cell parameters: I believe >> XDS does >> > >> > Phil >> >> > > > -- > Peter > > -- Peter
