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Old 11-07-2012, 06:09   #1
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HOWTO: Northern Great Lakes-Michigan Raster Chart Display Workaround

HOW TO: Use Michigan/Great Lakes Raster Charts on OpenCPN in A Manner to Inhibit Chart Display “Artifacting” (Display/Redraw Problems)
--> Link To File Download Page Correct As of 7/8/2012 <--
  1. Go to the following web page:
  2. Scroll down to the "RNCs by States:" area.
  3. Click on the "MI" listing.
  4. A popup dialog appears with a User Agreement. Scroll down to the bottom, where there is a line that says "Click OK to download".
  5. The "OK" will be highlighted. Click on that.
  6. The "" file downloads. (Firefox may open a separate tab or window before this begins.)

Step One: Choosing Directories
  1. Extract the "" to the directory/folder where you want to keep them. (Some people use separate directories for ENC (Vector) charts and RNC (Raster) charts.)
  2. Start OpenCPN.
  3. Click on the Toolbox (Wrench) Button.
  4. Click on the Charts Tab.
  5. Looking at the "Available Chart Directories" window, click to select the directory (folder) to where you extracted the "" file. (Ex. C:\MI_RNCs\).
  6. Click the "Add Selection" Button, located below the "Available Chart Directories" window.
  7. The directory path appears in the "Active Chart Directories" window, located below the "Available Chart Directories" window that we've just been working in.
  8. Look at the bottom of the Charts Tab dialog, where it says "Update Control".
  9. There are two boxes, one labeled "Scan Charts and Update Database" and another labeled "Force Full Database Rebuild".
  10. Since we are adding a new directory, ticking the "Scan Charts and Update Database" should be all that is required. However, I usually like to tick the "Force Full Database Rebuild" box and just create a new database for the entire program. Experiment to see what works best for your system.
  11. Click the OK Box at the bottom of the Charts Tab dialog.
  12. A Scan Dialog should pop up, showing a progress bar, indicating the scanning of the new directory with your new "MI_RNCs". (If you have selected "Force Full Database Reload", multiple progress bar/scanning dialogs will pop up, indicating the (re-) scanning of the old directories. This is normal in this case.)
  13. Once all scanning operations are complete, it is now time to create the "MI_RNCs" Chart Group.
Step Two: Creating A Chart Group
  1. While still in the Chart Tab dialog, click on the "Chart Groups..." Button, located toward the bottom-right of the Chart Tab dialog pane.
  2. The "Chart Groups" dialog pane appears, displaying two windows, one labeled "Active Charts" (on the left), and "Groups" (on the right).
  3. The directories where your charts are accessed are displayed in the left pane. Take note of the "MI_RNCs" directory listing but don't do anything just yet.
  4. Under the "Groups" window, are two buttons, one labeled "New Group..." and another labeled "Delete Group".
  5. Click on the "New Group..." button.
  6. A "Chart Groups...New Group" dialog box appears. Type in "MI_RNCs" (minus quotes) in the "Enter Group Name" text field, then click the OK Button.
  7. A new Tab will appear above the "Charts" window, named "MI_RNCs".
  8. Click on the "MI_RNCs" Group tab. (It may already be selected from the above operation.)
  9. Now, looking over to the "Active Charts" window, click on the "MI_RNCs" directory listing to highlight it.
  10. Click on the "Add-->" button, located between the "Active Charts" and "Groups" windows, and located above the "<--Remove" button.
  11. The "MI_RNC" directory appears in the "Groups" window.
  12. Click the OK Button (Chart Groups dialog).
  13. Click the OK Button (Toolbox dialog).
  14. Now, back at the chart window, Right-Click, then select Chart Groups > MI_RNCs .
  15. Now view the Northern Michigan Great Lakes Raster Charts without any display issues (or minimal, at the very least.)

AUTHOR NOTES, DISCLAIMERS, and OTHER MISCELLANY: I have experimented with this for viewing the Straits of Mackinac (pronounced “Mack-Ih-Naw”), Northern Lake Huron (Northeastern Lower Peninsula, Eastern Upper Peninsula, Les Cheneaux Islands, Saint Mary's River, Drummond Island, etc.), and have found it to be reasonably stable while using the above methods.

On another, semi-related, operationaI note, I am considering—at a much later date as of the writing of this document—a circumnavigation of the Great Circle Route, and have played around with OpenCPN around the Southwestern Lake Michigan Area.
Using another program—PolarView—as a comparison base (because is works well using both Vector and Raster with no indicated display artifacting), I have found that there are issues with Vector chart display of parts of the Calumet River and Chicago River areas, using only Vector charts.

PolarView—again only as a comparison base—displays the entire canal system from “Chicago-To-Missouri-To-Louisiana” with no artificating, whatsoever; this, I would assume, is what is desired from OpenCPN. I will experiment with a configuration, similar to that used in this document, and create another “HOWTO” for specific display problems related to viewing in certain areas.

Most of the “issues” I find occur in chart overlap areas, so it is my intention to suggest a “chart/directory scheme” that addresses these issues, ie, using only one type of chart. Also, as most of the United States Inland Rivers (Missouri, Mississippi, etc.) are in ENC/Vector format, I will only mention RNC/Raster charts where they are desired, and also where they may provide additional “visual” information on-chart. (The Chicago Area, as one example.)

Raster Charts are sometimes out-of-date with regard to certain features [marine railways as one example] so it always good to “Call Ahead” to find out “what is what” from the relevant authorities.

To The Point Above: I wanted to create a map feature in Google Maps that indicated a Marine Railway on a river in Michigan. I took this information from an “up-to-date” NOAA RNC/Raster chart. Well, after a lot of research, I finally ended up calling a local marina in the area-in-question, and found out that the so-called marine railway—which was, in actuality, not a “railway” at all, but a two-sling canvas hoist—had been discontinued for some years. The hoist was used to move boats from the lower-pool of a dam to the upper-pool, which then fed, by a continuance of the river, to a lake. Having been thereto armed with “better information,” I did an “Undo” to the Google Maps feature, chagrined, but wiser in the elements of doing more in-depth (pun intended :-P) marine feature research.
Disclaimer: Some people may not be experiencing what I am experiencing. Therefore, anything and everything stated, suggested, or recommended, is strictly from the point-of-view of the author, and does not represent any of the views of the developers or other users of OpenCPN.
This “HOWTO” is provided in the hope that it may be of use to those experiencing certain elements of “display artifacting” of the general area of the Northern Michigan/Great Lakes area. Additionally, This document is provided “AS IS” with no warranty as to the correctness of any information presented herein. Please use at your own risk and, of course, ALWAYS USE COMMON SENSE WHEN NAVIGATING! (If more people did this, we'd get into much less trouble on the water!) Always plan your route out ahead of time, and KNOW YOUR OBSTRUCTIONS!

Any suggestions for improvement of this “HOWTO” may be sent to the following email address: firefishe AT gmail DOT com . (Format done for spam protection. Replace the “AT” with “@” and the “DOT” with “.”)

Thank you for reading, I hope the foregoing has been helpful to you. :-) I look forward to meeting some of you on the water. Power or Sail, it doesn't matter! Just Get Out and Get Boating!!
--GreatLakesBoatr – 7/08/2012
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Old 11-07-2012, 06:12   #2
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Join Date: Jun 2012
Posts: 7
Re: HOWTO: Northern Great Lakes-Michigan Raster Chart Display Workaround

TO THE MODERATORS: I hope this wasn't "too over the top." ;-) I just wanted to share what has worked for me. I hope the Community enjoys this post and that it is helpful to all! Pleasant Boating, --GreatLakesBoatr
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