Chris Pelkie wrote: > >Hi There... > > > >I have problems in rendering slices of volume data. When I make plots with > >MapToPlane, Slab or Isosurface I sometimes > >get unsmooth picturesi, where even the grid is kind of visible. The effect is > >stronger on coarse grids and large gradients > >along the 45 degree line. I know this could be a problem for the renderer, > >but I know from other programs, that this > >could be solved. I experienced, that the error is greater when I import > >connection dependend data > >which is converted with "post" to position dependend data. > > > >I put two pictures on my website, which demonstrate the problem. > > > >http://www.nderberreth.de/IsoSurf.jpg > >http://www.nderberreth.de/CoarseGrid.jpg > > > >Does anyone know a solution how I can get smooth plots ???? > > > >Thank you very much !! > > In parallel, add a ShowConnections (color set to black) and Collect it with > the CoarseGrid plot. The answer should be obvious. The reason the image > looks coarse is because you are asking it to plot inherently connection > dependent data, so naturally the color is constant across a large area > (each polygon). Post'ing the data averages the values for each four > neighbors around a vertex, which is effectively a simple 2x2 box filter. > This does not increase your resolution. Look at the image with and without > Post with ShowConnections highlighting the connection boundaries to see > what it does. > > Here's the trick: you are thinking your data is connection dependent so you > are telling DX to import the grid using the same number of connection > elements as data elements. You need to fool DX by telling it to import the > same number of vertices (positions) as data elements. This will shift the > data over and down to the left half the width and height of a connection > element and then you can declare the data position dependent. Now, the four > position values will be averaged across the face of each polygon giving a > smoother appearance. > > So for example let's say you have 3x5 positions, therefore 2x4 polygons and > 2x4 data values. Simply tell DX that you have 2x4 positions and 2x4 data > elements and that the data is "dep" "positions". >
I actually do not get it how to do this. I am importing the data with the .general and a data file. So I define gridlines in the .general file and tell dx that I have connection dependend data. If I say the data is position dependend, I get an error. Do I havce to import the data in another file format ??? Also, when I import position dependend data I get sometimes unsharp plots, which are not that bad than the con. dep. ones. Is it possible to get smoother plots there ? Thanks Alex
