On Wed, 08 Jun 2005 22:19 , Jussi Laako <jussi.laako(a)pp.inet.fi> sent: We're talking apples and oranges here. You're talking about the real-time collection of multibeam. That is a piece of cake. I don't mean in terms of the actual beamforming but in the amount of data per second you have to deal with. The beamforming is really complicated. I'm talking about post-processing the data from 7 ships with dual multibeams plus 8 or so hydro survey launches running dual head multibeams plus a significant number of high-end sidescan systems plus a plane running hydro and topo LIDAR and hyperspectral. The ships collect data 24/7, the HSLs 10 hours per day. All of these approximately 300 days per year. The plane collects about 150 days per year, 5 to 6 hours per day. We're post-processing for hydrographic (and other) types of use. When you're dealing with tens to hundreds of billions of data points execution speed makes a huge difference. Yes, part of it is about how you write the code but if someone dumps a few billion data points on you and says "here, check these" then processing speed becomes extremely important. There have been some very good points made in this discussion and I will definitely investigate some of them. My problem here is that I've heard the same type of thing from companies and universities for way too long. Something along the lines of - "Really, you don't need to write your own processing code. We collected sonar data for a whole week and we didn't have any problem processing it with (fill in your favorite GIS or sonar processing package here)". Although this thread has about run its course, I would like to continue the discussion on sonar systems with you off-line if you are interested. Jan