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want to draw contour lines on loft

Discussion in 'Using Alibre Design' started by R-man, Jun 23, 2018.

  1. R-man

    R-man Senior Member

    Hi. I've forgotten what little I knew during a multiyear absence from using Alibre. To get back into it I am creating a contour map of my sloping lot.
    After a lot of 'surveying' and stretching of string, and adjusting in Excel, got elevation readings on a 4 ft grid (more or less). I created 17 splines running the length of the lot and (after creating closed figures) lofted them to create a solid with my lot nicely shaped on the top surface.
    My plan was to 'slice' the solid with horizontal planes to create the contour lines. I have no idea how to do this, at least no good idea. Any suggestions/advice will be appreciated.

    (I see I'm a 'Senior' member! Just by growing old I guess.)
     

    Attached Files:

  2. Lew_Merrick

    Lew_Merrick Alibre Super User

    R-man -- You will need a set of Sketches to create a L:eek:ft. Each of those Sketches can be Copied into a Drawing and then "ReImpotred" into the Drawomng for the Loft and overlaid to create your topographical pattern set.
     
  3. HaroldL

    HaroldL Alibre Super User

    rman,
    If you already have a Loft of your lot then what I would do is create your Planes (like in your uploaded model) so they stack up from top to bottom of your loft. Then on each Plane, starting at the Top, create a sketch that extends beyond or even with the perimeter of your loft and create an Extrude Cut toward the top. Then on the newly created surface start another sketch and select the Project to Sketch tool, select the cut face or faces and project it, or them, to the sketch. Next, with the sketch still active, select the Extrude Boss and extrude Up either to the Plane using the To Geometry option. Now repeat these steps all the way to the bottom of your Loft.

    When you are done cutting the Loft into layers create a drawing of your model and the Top view should have all the contour lines for your lot.

    Here are a couple of images of a quickly modeled Loft and a Package file of the model and drawing. I only did a few layers on the top to show the steps. To make the view a little more clear I Hid the Plane above the ones I was working on as I progressed down to the next lower plane. I think you should be able to catch on to the process with these files.
    ContourDrawing.png ContourModel.png
     

    Attached Files:

  4. R-man

    R-man Senior Member

    Thank-you Harold.
    Your solution gives me what I specifically asked for, however what I didn't clarify is that is that I also want to maintain the 3 dimensional aspect of the lot. Eventually I will place trees, a model my proposed construction, etc. Maybe even the neighbours' windows floating in space.)

    So based on your example, and more reading, I will try and create slices that maintain the slope of the lot on their edge (rather than square edges as in your example). I assume I can do this by making multiple copies of the loft and then intersecting each copy with a rectangular solid of appropriate dimensions and elevation. Then (I hope) when the resulting slices are re-stacked, the divisions between the slices will show as contour lines.

    Are there any reasons to think this won't work? As I write this it crosses my mind to ask: Is it possible to directly cut a solid in two? That would make my planned approach much easier.

    (Lew, I might misunderstand your meaning. I've already created 17 sketches, vertical cross sections of the lot determined by string and yardstick, and lofted them to create a 3D replica. Now I'm trying to somehow put visible lines onto that surface. I can't make sketches that represent the contour lines because I don't know where/what they are. This exercise is, in large part, to determine those lines.)

    Doug (R-man)
     
  5. R-man

    R-man Senior Member

    Now I have a new problem. My file (same one as uploaded) has lost the loft and all but one the 17 sketches! They are not showing in the rendering OR in the 'pane' on the left side of the screen. I downloaded the uploaded file to compare and it has the same problem. What could have gone wrong? ???

    The only thing I can think of is that when I looked at the "package" that Harold sent me, a pop-up asked me about if I should "restore" files, with the option to overwrite. I did NOT choose the overwrite option. Could this 'restoration' have corrupted my file or my system??
     
    Last edited: Jun 24, 2018
  6. HaroldL

    HaroldL Alibre Super User

    The file that I down loaded only had one sketch and no loft.:confused:

    One method would be to Delete all the Extrude Cuts and Bosses leaving the sketches. The contour sketches will show in the model but will not show on a drawing. And, they will not be constrained since the underlying geometry will be deleted.


    ContourSketchLinesOnModel.png
     
  7. R-man

    R-man Senior Member

    So that means that the problem happened as I was uploading the file! Now I understand the response I got from Lew. What you and he saw (and what I am now left with) is an earlier stage of development, when I had only one sketch drawn and the spacing of the planes was incorrect.

    Although I spent a lot of time creating the file, most of it was going through the trial-and-error learning curve. I have all the CSV files for the spines and for the extra lines needed to create closed loops, so rebuilding it should go fairly quickly. It's still a mystery what happened to my work. I don't know if there is an autosave function but if there is I will find it and turn it on. Or maybe if I search carefully I'll find an autosaved version.

    And thanks for your latest suggestion. I will add it into the mix as I continue with my train-and-error approach.
     
  8. Lew_Merrick

    Lew_Merrick Alibre Super User

    I highly recommend a trip to and through WizoScript as part of your "education."
     
  9. R-man

    R-man Senior Member

    Thanks Lew. I've been thinking of looking into it. I guess if I had built my project using WizoScript I could rebuild simply by re-running the script. I'm beginning to see the light!
     
  10. R-man

    R-man Senior Member

    Ok. I'm making great progress with WizoScript and thus with my project. However I have two minor issues, both of which I can work around, but I would like to better understand what is going on. I've attached a simplified script (as a text file) that demonstrates my questions.

    First, it seems that the statement "for i in range (1, 4)" loops 3 times ending with i = 3. I would not have expected this.

    Second, when I place points on a plane (parallel with the ZX plane) I get negative "z" values, even though all of my points have positive values.

    Hopefully someone will take a look at the script and provide an explanation. My thanks in advance.
     

    Attached Files:

  11. R-man

    R-man Senior Member

    oops! File needs a few newlines . . .

    Now file is readable but might not be runnable . . .
     

    Attached Files:

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