10 replies to this topic

[gvlisnas]

Hi,

I have a nautical map with a lot of vathymetric points that i want to create contours from.
I can use Arcgis or Surfer. In Arcgis using tin the contours are straight lines between the points with no curves. I want to smooth those contours but every contour must pass from the vathymetric points of the same depth. Any method i read or used, smooths the line a lot and misses the fixed points.

Is there any way to solve this?

Thanks in advance

[A. Fenix]

could you be more specific on how you are creating the contours from the points in Arc gvlisnas? it's always helpful to know your process steps in order to understand more fully your problem.

Thanks!

analisa

[gvlisnas]

The classic way i guess. I create a tin using 3d analyst and then from the same tool i create the contours. A second method i use is to create a raster with Surface Interpolation from Spatial Analyst and then from the same tool i use surface analysis. But it is slower than creating a Tin and the results are not exactly how i would like them to be.

edit:
Here is a little sketch i made tha explains my problem.
On the left is one contour, like the one that arcgis generates. The contours passes from the fixed point but connects them with straight lines.
In the middle is the result from smoothing the line from the arctoolbox. Notice that the contour doesn't pass from the fixed points.
I want to create a contour like one on the right. Smooth line that passes from the fixed points (bathymetric points)

Attached Files

•  1.jpg   128.45K   65 downloads

[Sky Schemer]

Manifold has a spline function that will take line segments and add points to make it more "curvy". The beauty of this function is that it preserves your original points. It doesn't make actual spline curves: it turns your lines into lines with many more line segments, but you can control the level of segmentation and your results will look a lot like a true curve. So, you could take your contours generated by Arc or whatever, import into Manifold, run the spline function and then re-export. This will cost you a $245 Manifold license, of course, but if you have Arc with extensions, that's pocket change, right?

See attached. Of course, the risk here is that the splining process changes the shape of your line, and if your contours are really close together, the resulting lines may intersect here and there.

There might even be free or cheap-ware tools that can do this, too, though I'm lazy and haven't looked.


Cheers,
John

Attached Files

•  before.png   5.41K   49 downloads
•  after.png   6.59K   54 downloads

[gvlisnas]

Thanks John that is exactly what i want.

In the meantime i found another solution that works. Import in Autocad, preferable Autocad Map and then use the "fit curve" command to the polylines. Smooths them good and preserves the points you want. Obviously that triggered another problem that i'm working on right now. But that commands works. Thanks for your help!

[frax]

gvlisnas - what is your experience in preparing them as bezier curves in an ArcGIS geodatabase?

[gvlisnas]

gvlisnas - what is your experience in preparing them as bezier curves in an ArcGIS geodatabase?

Your question prompted me to google it and Arcgis does have this feature!
Didn't know it. Apparently with the smooth line tool from Arctoolbox you can use the bezier interpolation. Actually i used the tool before but completely missed the choice. I made them using the PAEK method which misses the fixed points so i thought that it can't be done in Arcgis. Do you mean this tool when you ask me about preparing them for an ArcGIS geodatabase?

I will compare the results of this with the "fit curve" command in Autocad and will get back with the results. Thanks frax you made my day!

[frax]

Acutally I have no experience with that at all, I just know that it is in there, and that you have to use a geodatabase (and not a shapefile) to use the tool... I have been meaning to play with it, but haven't gotten that far yet...

[DaveB]

Cartographic Representations in ArcMap will let you curve the representation of the lines without changing the underlying geometry.

[A. Fenix]

I've tried utilizing the "power" of cartographic representations in ArcMap and found myself frustrated. Of course, I was on a tight deadline and didn't really have the time to read the 20 page How To guide... anyone out there find that Cartographic Representations have really helped their mapping in ArcMap?

I'm still using my old tricks...

Analisa

[peanut]

I've tried utilizing the "power" of cartographic representations in ArcMap and found myself frustrated. Of course, I was on a tight deadline and didn't really have the time to read the 20 page How To guide... anyone out there find that Cartographic Representations have really helped their mapping in ArcMap?

I'm still using my old tricks...

Analisa

I spent some time last week looking at Cartographic Representations. I can see how using them will be beneficial in the future. There are many times where I maintain two versions of my Geographic data. One dataset will contains the correct coordinates for the data and the other dataset contains offset coordinates that are used for cartography. Cartographic Representations will eliminate the need for maintaining multiple datasets in many cases.

On the downside working with Cartographic representations on data that is stored in my organization's enterprise Geodatabase might prove to be difficult in terms of editing rights to the Geodatabase.

Cartographic Representations IMO will eventually streamline the cartographic workflow within ArcMap for most users but will not eliminate the need or convenience of editing the final map product in a package such as Adobe Illustrator.

Rich