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View Full Version : surface problem weeding and supplementing factors



valejandro_ibarra
2010-08-04, 05:17 PM
so i have a contour file that has contours every 20 m vertical, so when i created a furface using this contours it has "blank" spaces , can anyone help me this problem, i know it has something to do with the weeding and supplementing factors but how do i adjust them.

BTW in already using minimize flat areas

see the pics

Seems like i need an option to do "less straigh" lines

sinc
2010-08-04, 06:49 PM
Those look like flat areas to me. What sort of settings are you using for "Minimize Flat Areas"?

valejandro_ibarra
2010-08-04, 10:10 PM
This one see the pic

sinc
2010-08-04, 10:54 PM
Maybe try turning off the "Swap Edges" option, and see if it makes any difference. But it probably won't.

I think that's about as good as you're going to get. It looks like you have 10x as many contours in your resulting surface as in your starting surface, so it's no surprise that you're seeing some relatively flat areas. Your source data isn't accurate enough to create good contours at the level you have them in your second image.

Keep in mind that creating a surface from contours is the worst possible way to create a surface. It can introduce a lot of error. For example, if you're starting with 1' contours, you can have as much as 1' of error at any single point in your resulting surface. Usually the error is within 1/2 the contour interval, but it can be as great as the contour interval in some cases.

It is far more preferable to get TIN triangles or LandXML from your source. Or Points and Breaklines. So if it's an option to go back to the source and get the surface data in some form other than contours, that would be the best thing to do.

jmeyer.186809
2010-08-05, 04:38 PM
Maybe try turning off the "Swap Edges" option, and see if it makes any difference. But it probably won't.

I think that's about as good as you're going to get. It looks like you have 10x as many contours in your resulting surface as in your starting surface, so it's no surprise that you're seeing some relatively flat areas. Your source data isn't accurate enough to create good contours at the level you have them in your second image.

Keep in mind that creating a surface from contours is the worst possible way to create a surface. It can introduce a lot of error. For example, if you're starting with 1' contours, you can have as much as 1' of error at any single point in your resulting surface. Usually the error is within 1/2 the contour interval, but it can be as great as the contour interval in some cases.

It is far more preferable to get TIN triangles or LandXML from your source. Or Points and Breaklines. So if it's an option to go back to the source and get the surface data in some form other than contours, that would be the best thing to do.

I agree with SINC. Using Contours to create a surface is bad news unless thats all you got. It's not accurate enough. All it does is mimics the contours and creates uniformed slopes and flat spots between contours.