CREATING 2D CONTOURS

[jaredmccullough]

Hello,

I was referred to this tool/forum by individuals at cadtutor.net as they thought it might be applicable to the project I am working on. Essentially what I am working on is using AutoCAD based drawings to create noise contour diagrams or "Isopleths". Attached is an example. This being said it is similar to that of most other contour diagrams in that the theory used behind it is interpolation. Unfortunately from my understanding this cant be done easily in "Vanilla" AutoCAD and that is why individuals referred me here.

What I took from it was that the Surface tool could be used to create these contour diagrams. I guess what I am looking for is a little help in how to use the CADTOOL to achieve my goals (Their is no tutorials available from what I could see)

Attached is an example of the map I am trying to change into an isopleth/contour diagram. The noise measurements are on a seperate layer of their own an essentially could be similarly compared to that of using elevations to create contours.

Thanks for your help and I hope to get some advice

[Lars]

Hi!

First you set all layers off but the layer with noise values (text). Next step is to create a surface with noise levels instead of elevation. Use the Create Surface command. In step 1 you set what kind of input data CadTools should use. In your case you should use Text, when that option is checked you get a second option to treat text strings as values. This option is handy if the text has an elevation that is useless (elevation 0). In your case you should use that option to let CadTools read your noise levels as elevations. I'm not sure how this works with MText.

Set Triangle output to "Save to file" and execute. Use the "Edit/View Surface" to examine your surface data (tab Surface data). You can open a new drawing and plot the triangles and use AutoCADs Orbit command to rotate and see if there is something wrong.
Delete unwanted long triangles and save the surface (overwrite)


Use the Surface Contours command to generate contours. Read CadTools help file about smoothing contours.

I think you'll have some work to do getting the data correct, you have all noise values in "PaperSpace" with small distance between the points. CadTools is developed mainly for the model space.


Hope this helps

[jaredmccullough]

Lars,

Do you feel that this task is something that can be accomplished using CADTOOL?

Also for  a majority of the noise values I can use the CHSPACE Command and move them into model space if you feel this would help? Although there are two drawings that I have that will not be plausbile to do that in.

Im a little confused on the workflow for this:

1. Open original drawing and turn all layers of except the "Noise Measurements"
2. Use the CADTOOL create surface and create a seperate .tsd file with triangulated data
3. Load .tsd file into Edit/View Surface which brings it back into the drawing
4. Then use create surface contours command (which requires donation)

Correct

[Lars]

I do belive it can be done with CadTools. If you provide me with some data I'll try to generate some contours. There seems to be something odd with your coordinates, the distance between points are small? Do you have the noise data in any other format, in real coordinates?

The workflow you described is correct. The idea is to create a surface with noise level as elevation and then create contours.
Another problem with your data is that it's in MText, there's a bug in CadTools. This can be solved by exporting the data to Excel and then draw them back as points (booth these commands are included in CadTools).

I've uploaded Build 686 that fixes the bug in the triangulation option "Use text string as eleveation" if you use MText. And Build 687 that fixes some issues with gaps in the contours.

Download the update and use it on your data.

Attached file include some contours that I generated based on your data (moved to Model Space and splined with AutoCAD)

/Lars

[jaredmccullough]

Lars,

I have a few questions. First it seems as though you were able to get the end result.

1.) You stated that you moved the data to model space (I am assuming using CHSPACE) do you think that the data needs to be in model space or is it possible to do with data in paperspace as well? I have one or two drawings in which are interior views where I used the same model space but created seperate viewports to represent different floors of the building.

2.) Could these contours be adjusted to a scale in of 5 increments instead of 2?

3.) Could these contours be filled in with trasparent coloring similar to that of other Noise Isopleths (Google Search if you have not seen one) to represent transitions of noise readings between contour lines.

4.) Do I need to transfer to excel or since you were able to update the software does that eliminate that step. As well the example you provided had the contour above the original drawing how do you put that into place?

5.) Lastly would you be willing to provide a little assistance as I try to learn the concepts?

Thanks for all your help

[Lars]

Hi!

1.   I used the CHSPACE command (never heard of it before) to move your data to Model Space before I triangulated it. Most of CadTools commands that plot to AutoCAD are designed to work in Model Space. You need to work in Model Space while plotting contours.

2.   You can set interval for major contours any value and also set a value for Minors per Major. To get a increment of 5 you can set Major to 10 and Minors per Major to 1.

3.   I’m sorry but CadTools can’t create that kind of contours however you can fill closed contours with hatches (solids) manually.

4.   You don’t need to transfer data to Excel, the update solved that issue.

5.   Yes, I can assist you. I'll provide you with a detailed description by mail of how I managed to contour your data.

/Lars

 

[Lars]

In this video demonstration you'll find how to create surface contours based on your data.
http://www.glamsen.se/Download/CadTools/Media/Noise_Surface/NoiseContours_controller.swf

There is an update (Build 688) that fixes a bug when annotating to nonexistent layers.

/Lars