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rhumbaflappy

Error 621 - looking for the key to the puzzle

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Hi guys, I have just spent time learning the techniques for using Ground2k. Its all coming together, and I'm enjoying the challenge of marrying the srtm elevation data to a topo map, and adding lakes, etc. Good fun.Only bummer is this error621, lake/line crossing itself. Now I keep thinking I've got it, and yet I don't. I'm trying to add coast with "poly with shore", making the lmw land. I've tried clicking off "joins ends of line", which seems to take away a chance for the line to cross itself, but this doesn't fix it. I've tried not crossing area boundarys....no go. I find that VERY simple shapes don't produce the error, but tracing real shorelines does produce it. For a while I thought the "surf" option for the line was at fault, but a red herring. Once it worked, but when I changed the poly type to land, it didn't.Can someone lay out the dos and don'ts that can make this error show up? Am I trying something that is not possible? Must you add the lmw land seperately from the coastline?Could it be a limitation of the underlying landmask/watermask?And another question, if I go into the attributes by rightclicking on a coastline in ground2k after its selected, can I edit the attributes? I know I can change the boxes, but I don't know if the program is accepting the changes. Had many other questions also, but searching the arheives of this forum answered all but this one annoying deal....Thanks in advance,Bob Bernstein

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Hi Bob.Sometimes an LWM poly ( water or land ) will cross itself if the defining edge ines sre too close together. Also, you don't need to "close" the poly... the start and end points should be separate.Usually, G2k tells you where the error is located:http://forums.avsim.net/user_files/38334.jpgIf you can't find it, sometimes Christian can help if you e-mail him the LWM file ( don't send the background image).Dick

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THanks Dick, wish it was so simple. Certainly, I assumed I had what you drew, from the text of the message, but we're talking a coastline here, and the more the error has afflicted me the more simple my test pattern has become. I can get the error with a relatively simple line that never turns back on itsself. Has anyone attempted to draw the coasline of an island and had this problem? I go to the point mentioned in the message, and I'm in the middle of a perfectly straight stretch of coast. Upon deletion of the point in question, the error just shifts to the next point.

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Hello Bob,It would help a lot and we would not have to guess if you could post a screenshot of - the Ground2K workspace with your problem coast (like what Dick has posted); - the Attributes window for your coast.Just some clarifications: a coast (Land Mask) and a line (beach, bank, etc.) are two different things. A curve representing a coast may not cross itself, because a coast is a polygon - if the curve crosses itself, then this becomes two polygons. A coast will mistakenly cross itself if: 1) you draw the curve over itself; 2) you backtrack while drawing the curve; 3) you try to close the curve to make a closed polygon and your ends cross each other; 4) any other possibility that I have not thought of.A line CAN cross itself with no problem.Before Ground2K, we had to draw coasts and lines separately. Ground2K offers the possibility of combining the two if you desire - just draw one curve and Ground2K will make a Land Mask polygon and place a line (beach) along the edge of your curve. You must be careful about how you use the option to "Join ends of line" when using this possibility. This would ONLY affect the line (beach) anyway, but will continue the beach from one end to the other of your curve, thus placing a beach within the coast. But, otherwise, this poses no particular problem and is very useful.As for modifying the attributes of your curve by right-clicking, as you may have noticed by now, this is perfectly acceptable and shows the thoughtfulness of Ground2K. All changes immediately affect the curve.Please don't give up - the solution to your problem is most likely quite simple.Best regards.Luis

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Tanks again for all who answer so quickly, and better I could do.Christian

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Hi all, Luiz, Dick, and Christian...1. My project is really just a vehicle to learn ground2k, but I chose to decorate Orcas Island in Washington state. I first made lakes and roads, which worked out well after a bit. PICTURE ONE2. Now I decide to add poly with coastline around my excellant topo map. I start with the settings shown in PICTURE TWO (also I made the lwm tab set to land).3. Then I drew about 4 points of poly with coast starting at the top right of the circled area showing in PICTURE THREE.This compiled just fine, no errors.4. Then I selected this portion of poly with coast,clicked on the button to "extend" a line, and doubleclicked near my first line, got the cursor to be rubberbanded to the last point, and proceeded to add more points.Now it gives me the error 621 shown in PICTURE THREE.A close up is shown in PICTURE FOUR.The poly with coast was drawn from top right to point A in step 3. After adding the portion of poly with coast to the left and below point A, I get the error. The point that is mentioned in the error message is point B. Interesting, huh...a point that had previously NOT been in error is now in error after only adding to the line starting at point A.Clearly something is amiss, likely my being inexperienced, but its hard to know what to do to fix it.Help is appreciated. my lwm file is attached in the zip file.Bob Bernstein

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funny, my attachments aren't showing up.that's frustrating. I'm really trying to explain all this....grrr.Must be a server problem, I've uploaded the attachements but they don't get added to the attachments box, like they should.Bob B

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Hello Bob,I hate making guesses, it is a frustrating exercise. But, until you can get attachments to work for you, perhaps you could consider the following:A coast is a Land Mask. A Land Mask is a polygon.A polygon is a CLOSED many-sided figure.When you draw a coast, you usually draw only the part that fronts the water.Ground2K will ALWAYS close the curve by drawing a straight segment from one end of your curve to the other.This can lead to an error. See the following example:http://forums.avsim.net/user_files/38898.jpgI have drawn a harbor, but note what happens if Ground2K completes the curve by drawing a straight segment from one end of my curve to the other - the curve would cross itself and return the error message.The solution is to extend your curve in such a way that the final straight segment will not cross over the curve. There are numerous ways to do that; just use whatever solution you prefer. Here is one possible solution:http://forums.avsim.net/user_files/38899.jpgThis is, of course, only a guess and could be wrong. But, there is not a lot that can go wrong with Ground2K.Best regards.Luis

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Thanks for your effort, and how in the heck are you able to include your images?I"ve tried and tried, and here, you post with two pictures embedded right in the message.....Are you doing something different than the "attachment" thing at the bottom of the typing box?You may have guessed right, btw. I would assume that avoiding this error would be easy if you just continue your coast all the way around an island...I'll try it tonight.I must be the only one unable to post attachments, cuz no one else is talking about it. Funny huh. Posted for help in the forum help forum, but no reply, sent a note to Ken Salter, been ignored, and now you post attachments.hmmmmm

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Hi Bob:what is a man without attachments :-)Just for double-checking, here's what I do:1. Click on 'Choose your attachments'2. In the new window, browse to and click on your image3. Select the image type, .jpg or .gif, and make sure it meets the 700 px width, 125kB size limits (otherwise you'll get an error message)4. Select "Check this box if you wish to embed attachment URL in the message text box"; this is not required but will allow you to place the image(s) anywhere in your message5. Click upload file and wait for the confirmation message6. Now your image will be listed in the separate Attachment line and also as a URL placed at the bottom of the message window. The first thing I always do is to click on 'preview message' which should show the image at the bottom of your message (assuming you have typed something in already).7. To move the image to a different place, highlight the URL (via double-click), then Ctrl-X (cut) and Ctrl-V (paste) anywhere you want.8. Do a final preview before hitting 'Post message'Hope this will get you going.Cheers, Holger

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Hi Bob:testing attachment...http://forums.avsim.net/user_files/38991.jpg... seems to be working for me. Must be your Karma - try clearing your mind of any negative thoughts before doing this ;-) and don't forget proper breathing...Sorry it ain't working for you - very strange.Cheers, Holger

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Hmmmm, ain't that interesting! I tried it this morning, and the dang thing didn't show up. (nice pic btw) oooohhhhhhmmmmmmmmmmmperhaps that's why my appeal for help has been a bit ignored....perhaps a local "Bob" problem...operator error? Thanks,B

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Hi Bob.Why not e-mail me and attach a zip of the whole works to me? ( LWM file and the background image ).mailto:ludowr@charter.netDick

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