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Tec Plot Doubt :: Regarding Extract> Precision Line

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Old   April 9, 2022, 10:54
Default Tec Plot Doubt :: Regarding Extract> Precision Line
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KSD
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Hello, I am actually facing trouble in creating an exact line using Extract> Precise Line. I am not able to understand when I try to manually input the coordinates of the line, Tec plot creates a line which is shorter than the specified and also at different locations of the domain.

But when I copy/paste the approx. coordinates by using the probe tool, I can see that the line that it generates is similar to what I want to generate using coordinates I want to specify.

For e.g As you can see int the first image, the x coordinate of the line I have specified is around -1.8 but the Tec plot is plotting a line somewhere else.

(Image 2) But when I specify the coordinates of two end points of the domain using probe value, I get approximately the line I want to generate.

Could you help me to avoid this issue, I don't understand why it is happening.
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File Type: png Manually Specifying The Coordinate.png (79.9 KB, 25 views)
File Type: jpg Using Probe Coorfinates.jpg (76.4 KB, 15 views)
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Old   April 19, 2022, 22:33
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Scott Fowler
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In the first image it appears that the Y-position of the line may be right at the Y-minimum value. In that case there may be numeric precision issues. Do you get the same problem if you increase the Y-position value by a small epsilon?
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Old   April 20, 2022, 02:25
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@wsfowler Thanks for responding.

Yeah, that's how I am managing to get the line for now. I am just slightly increasing the y value to get the line properly across the wall.

Is there any way to limit the precision of Tec-plot to certain digits? Or is this the only way to solve this problem.
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Old   April 20, 2022, 02:27
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@wsfowler Thanks for responding.

Yeah, that's how I am managing to get the line for now. I am just slightly increasing the y value to get the line properly across the wall.

Is there any way to limit the precision of Tec-plot to certain digits? Or is this the only way to solve this problem.
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Old   April 21, 2022, 16:25
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The way "Extract Precise Line" works is that it effectively does a "Probe" of the data at each point along the line. For the probe to be successful the probed location has to reside within a cell. So setting the Y-value to the exact Y-min will almost always cause a problem. The only reliable solution is to use the small epsilon to ensure the extracted line intersects a cell.

Another option could be to flip to 3D and place a slice, which will result in points extracted from the grid edges, rather than evenly distributed points along a line (which is what extract precise line does). But again, you'll need to ensure the slice is positioned slightly inboard to ensure it cuts through a cell.

Hope that helps.
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Old   April 21, 2022, 18:22
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@wsfowler Thanks a lot, it surely helped me a lot.
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