SR SSD 99-28

Technical Attachment

Evaluation of D3D Development at Forecast Systems Lab

Scott Plischke
NWSO Amarillo

During the last week of October and the first week of November 1999, I had the privilege of representing the Southern Region in an evaluation of D3D at NOAA's Forecast Systems Laboratory (FSL) in Boulder, Colorado. As part of FSL's continuing involvement with NWS field operations and forecasters, the regions were invited to send individuals to Boulder to review their progress on enhanced display software. Forecasters will be familiar with AWIPS' D2D. As the name implies, Display Three-Dimensional, or D3D, allows users to view model output and real-time meteorological data in a 3-D interactive display. It is part of the WFO-Advanced system development aimed at providing an advanced workstation to operational forecasters.

D3D is based on Vis5D from the University of Wisconsin. Basically, D3D is a modified and improved version of Vis5D with the user interfaces redesigned to appear and behave like those in D2D. D3D displays model output in isosurfaces, plan view contours and images, cross section contours and images, and volume renderings. There is also a wind trajectory tracing, an interactive sounding tool, and a probe for 3D sampling. Following are a few comments based on my experience with the new software.

I found D3D to be relatively easy to use. I credit this to its similarity with D2D. It took some time to get used to the mouse, however, since the three buttons take on different functions depending on which of the six modes (normal, sounding, trajectory, etc.) you are in.

D3D's isosurface renderings were impressive. Some fields, such as relative humidity and wind speed, displayed very well in isosurfaces - provided the threshold level was set high enough. For example, an isosurface of 80 kt wind speed provided useful information, but an isosurface of 10 kt completely filled and obscured the view box. I also found that overlaying two isosurfaces was the practical limit; any more created clutter with one isosurface blocking the others.

I found D3D's vertical cross sections and horizontal plan views to be very useful. These are two-dimensional displays and are available in similar form on D2D. In D3D, however, the user can use the mouse to quickly drag the plan view to any level and the cross section to any location. I really enjoyed this degree of interaction.

The sounding tool on D3D is another strength of the system. It allows the forecaster to move a mouse cursor over a geographic area and have a model forecast sounding interactively display. I was impressed with this tool and its ability to rapidly sample the vertical temperature, moisture, and wind fields over any given terrain.

Another beneficial feature of D3D is the trajectory tool. It lets the forecaster formulate a trajectory tracing over a location at any level. A trajectory can be constructed to show the track followed by a parcel of air after a given starting time. It can also show where a parcel will travel to over a period of time. Parcel ascent and/or descent can be examined on the tracing when the display view box is tilted to a side view.

As for system performance, the D3D evaluation was conducted on HP workstations that were more powerful than the J200s currently used in AWIPS. On the faster FSL hardware, D3D performed exceptionally well. It responded immediately to user inputs. I had the opportunity to use D3D on the slower J200s and was disappointed with the performance. Simply tilting the view box with several images loaded resulted in a noticeable and annoying jerking. FSL is developing a Linux port of D3D so there is the possibility that a high-end Linux PC can be used inside the AWIPS firewall to run D3D.

When can NWS field offices expect to receive D3D? The FSL D3D team could not provide a definitive answer to this question. At one time D3D was apparently slated for AWIPS Build 5, but that is not currently the case. Based on my evaluation it appears D3D could be useful for forecasters well before the AWIPS workstations will be able to support it. Perhaps a logical next step might be to use a Linux PC inside the firewall at a few sites to further evaluate its potential for operations.

Additional information and a look at some of the D3D products can be found at the following related Web sites.

WFO-Advanced D3D (

Vis5D Home page University of Wisconsin (

Vis5D Page of the NCEP Environmental Modeling Center ( ).