2. Our technology and philosophy for fishing contours is constantly evolving and improving. Much of the following data is subject to change. This powerpoint is meant to serve as a reference for fishing contour philosophy and the tips and shortcuts we’ve found effective along the way. 12/7/2010
3. Evolving Philosophy 2009.5 Fishing contours were new to us all. We didn’t foresee how extensively or in which markets our customers would use them. During QA we used fishing contours to find large dem problems; we didn’t make the time to fix the little gaps, jumps, or stacks. We did a lot of manual editing (clipping against land) and we excused a lot of inconsistencies because of the small scale of our charts. Etc. 12/7/2010
4. 2011 Fishing Contours should flow through a card in a natural and logical manner. No jumps, stacks, mismatched patterns No hiccups at tile or template borders No crossing Stacking should only be present in places with massive depth changes and the contours should still “flow.” 12/7/2010
5. Tips for FC QA Creating pseudo depth points Stamp bar See Hong’s 12.3.2010 email “Tip of the week - create pseudo depth points.” Copy and paste You cancopy more than one point at a time – if you have two minor entities with a pseudo depth points (pdp) along each boundary, select both points>copy> escape until nothing is selected>right click where you’d like to drop the points>paste. 12/7/2010
6. Seeing the changes: Color by feature (recommend coloring soundings) Color by modified object (allows you to see which areas you already addressed vs old pseudo depth points Toggling Areas and Grid on to see where problems are likely to occur, then back off to see the line interactions only. Remember to use your depth and approx depth contours. Keeping these features visible will prevent you from trying to use pdps which conflict with the charted data. Remember that bathy contours are used off the U.S. coast. In areas with bathy data the regular contours and soundings will be flagged not to factor into the dem. Remember Karen’s suggestion about using DEM values when trying to get adjoining dems to agree. 12/7/2010
7. Seeing the changes (continued) L-flag masks (these are tricky, please feel free to ask) Areas > 0X00000383 will allow you to “mask” 30m dem templates so that you can select just the 90m. (< 0X00000383 will mask the 90m dems.) Lines > 0X0000076C will allow you to “mask” lines shallower than 190m. This will declutter your screen but still show 192-220m overlaps (30vs90m dems). Points > 0X0000076C will allow you to “mask” points shallower than 190m. Toggle is Alt-3. (If you clear your l-flags to 0 you’ll have to “unmask” to reset the value.) These masks should be used carefully and will be of most benefit in areas of very dense data. 12/7/2010
8. Tired of dealing with both 30m and 90m dem templates? You can use the sql filters displayed here to import only the templates you need. 90m Why does this make me think of Jerad? 30m 12/7/2010
9. Where do I put the point? Originally we put pseudo depth points (pdp) at the corners of dem templates – times have changed. The dem generator will use corner values automatically, whether they’re set as pdps or not. The most effective place to put a pdp is at the greatest distance from the boundary where it will still be used in the triangulation. 12/7/2010
10. The point in the corner has very little effect on the dem – the one furthest from the top and left is the most effective To fill out a contour which flattens at the adjacent template edge, three points can offer the fishing contour a curve to follow. To fix a corner issue, two pdps at 45° might be more effective than one. This would be the approach for fixing hiccups between adjacent dems where the lines are slightly disjointed. 12/7/2010
11. If dropping points of like values doesn’t generate dems properly, try dropping points in the next level up or down to force the contours into the correct path. After 12/7/2010
12. Using the 3600m pdp didn’t pull the dem down here. 12/7/2010
13. Adding deeper pdps nearby pushed the dem and fc into the desired location. 12/7/2010
14. What do we fix?! *subject to change* Here we need to fix both the gaps along the y-axis and the disjointed contours along the x-axis. Note the gaps below would be invisible with the grid on. 12/7/2010
16. Here is a conflict between the 30 and 90m dems, stacking, and an absence of data on the western template. FIX A deep pdp on the western template would allow the eastern dems/contours to space out more logically. 12/7/2010
17. FIX Using copy/paste to preserve database assignment and spacing of pdps. 12/7/2010
18. At horizontal minor entity boundary the contours are disjointed. Also there is a visible discrepancy at the interior 30m dem intersection. A few pdps along the minor entity boundary would iron out this fc bump – we need to fix these. 12/7/2010
20. Types of problems we still can’t “fix” should be limited to large differences in scale. 12/7/2010
21. Gotchas Some pdps previously generated are named Autoguidance – regardless of l-flags these are not used by the dem generator. If you copy and paste one of these you will need to strip the name. When generating fishing contours for 30m dems, you will be asked if you’d like to delete previously existing contours – this will delete all 30m contours within the minor entity. If you only want to partially regenerate the 30m contours you will first need to select the dem templates – special>marine>contours>delete generated fishing contours for template. Let’s continue to communicate with one another. As processes and expectations continue to change it’s important that we share information and help one another achieve the best possible product. 12/7/2010
