Opened 6 years ago
Last modified 6 years ago
#1226 new defect
aliasing problem in 2D q rotation?
| Reported by: | pkienzle | Owned by: | |
|---|---|---|---|
| Priority: | major | Milestone: | sasmodels 1.0 |
| Component: | SasView | Keywords: | |
| Cc: | Work Package: | Plotting/Graphing Enhancements |
Description
Consider the following image: there appears to be an aliasing problem depending on quadrant.
Created using:
sascomp ellipsoid -2d -nq=128 theta=60 phi=45 -pars -midq radius_polar=250 theta_pd=5 -double!
The problem persists in single precision running on the GPU and long double precision running on the CPU. It is still there for -nq=127. It is less visible for -nq=256. It does not appear to be a plotting issue.
Attachments (1)
Change History (5)
Changed 6 years ago by pkienzle
comment:1 Changed 6 years ago by pkienzle
comment:2 Changed 6 years ago by pkienzle
It is not the model, and not the jitter:
sascomp parallelepiped -2d -nq=128 theta=60 phi=45 -pars -lowq
comment:3 Changed 6 years ago by pkienzle
- Priority changed from major to minor
Okay, not a modelling issue. The problem comes from the rebinning algorithm in the plotter, which takes arbitrary qx,qy,I data and puts it into a regular mesh. The code is in sasmodels.data._build_matrix, which was copied and modified from sas.sasgui.plottools.PlotPanel.
This should still be fixed, but it is a minor problem.
comment:4 Changed 6 years ago by butler
- Component changed from sasmodels to SasView
- Priority changed from minor to major
- Work Package changed from SasModels Redesign to Plotting/Graphing Enhancements
