This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
Greetings Bob, Would you mind sending the cdl file? I'll generate the netCDF file locally and try to see what is going on in the 3D displays. Cheers! Sean > Hello - > > We have a user who has a netCDF file whose 3D data may not plot correctly > based on the sampling mode. It appears that Weighted Average works better > than Nearest Neighbor, but both have their bugs. If you want a sample netCDF > file as well as the *.cdl file that created it, please let us know. Any > ideas of what may be going on? > > Thanks! > Bob Carp > > ----==== Inquiry ====---- > 1465 > > ----==== Summary ====---- > In a netCDF file, the 2D field plots correctly, but the 3D field may not plot > correctly dependent on sampling mode. > > ----==== Request ====---- > 2013-05-07 - Bob Carp > Joleen has a netCDF file that she created from a *.cdl file using ncgen. > This file contains 2 arbitrary pressure levels, and random temperature values > that plot out at different lat/lon points (almost in the structure of a 10 x > 5 grid). After adding this file, you can display a Value Plot display of the > 2D field fine with Weighted Average or Nearest Neighbor sampling modes. The > problem comes when you try displaying the 3D data: > > - When using Weighted Average, select the 3D field, a pressure level, the > Value Plot display, and Create Display. The data values displayed do not > match what is in the *.cdl file. Some lines of numbers are repeated, and > some values don't plot at all. In the Layer Controls (Displays tab), if you > change the level, and then change back to your original level, the data > displays much better (matches up with what is in the *.cdl file with the > exception of a little bit of interpolation). > > - When using Nearest Neighbor, select the 3D field, a pressure level, the > Value Plot display, and Create Display. The data values displayed do not > match what is in the *.cdl file, and messing around in the Layer Controls > (Displays tab) does not correct the values. > > This was tested with both McV and IDV nightlies dated 05/07. > > 2013-05-06 - Bob Carp > Joleen's initial email to the help desk: > ---------------------------------------- > Bob was looking at this with me. When I display 2D values, the data displays > monotonically, the same as it is written in the file. > > However, the 3D grids seem to use the wrong neighbor when displaying (nearest > neighbor is default for my setup). > > Check the input data object with > a=selectData() > print a > > 2013-05-06 - Bob Carp > I added test.cdl and test.nc to /home/mcuser/inquiry-data/1456 > > 2013-05-06 - Bob Carp > Joleen has a netCDF file that has 2D and 3D data in it. The 2D data displays > fine with the Value Plots display type. When you display the 3D data with > the Value Plots display, not all of the data is displayed, and some of it is > displayed twice. Doing a grid table display of the data works fine (data > does not repeat, and all data is listed. Here is how the 3D data looks in > the .cdl file and in the Main Display window. > > In the .cdl file In the Main Display window > 0 1 2 3 4 0 1 2 3 4 > 10 11 12 13 14 20 21 22 24 25 > 20 21 22 24 25 30 31 32 33 34 > 30 31 32 33 34 30 31 32 33 40 > 35 36 37 38 39 40 41 42 43 44 > 40 41 42 43 44 40 41 42 43 44 > 45 46 47 48 49 50 51 52 53 54 > 50 51 52 53 54 50 51 52 53 54 > 60 61 62 63 64 70 71 72 73 74 > 70 71 72 73 74 70 71 72 73 74 > > This has been tested in the 1.3b1 nightly from 05/06, 1.2, 1.01, and 1.0. I > also tested this with a recent IDV 4.0u2 nightly. This was tested with both > Weighted Average and Nearest Neighbor sampling modes. > > > ################################################################################ > > http://dcdbs.ssec.wisc.edu/inquiry-v/index.php?inquiry=1465 > > Ticket Details =================== Ticket ID: JXK-429403 Department: Support IDV Priority: Normal Status: Open