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I came across a pretty interesting issue where I am seeing artifacts around the center of a seven point spline.
The fifth-degree spline is formulated with seven control points. The details can be seen in the example scripts I've attached, but here is the symptom:
The x-axis on the plots are "time" - the spline is evaluated at each successive value every 1ms.
Anyway, the spline is moving along smoothly and then around u = 0.5, there is a discontinuity. This plot was generated using the artifact.c example. Here is the same data in table form:
u
x
y
0.499531
-127.507957
-189.170307
0.499569
-127.507462
-189.170394
0.499607
-127.506967
-189.170481
0.499644
-127.506484
-189.170566
0.499682
-127.505989
-189.170654
0.499720
-127.505494
-189.170741
0.499758
-127.504999
-189.170829
0.499796
-127.504504
-189.170916
0.499833
-127.504022
-189.171001
0.499871
-127.503526
-189.171088
0.499909
-127.501846
-189.171385
0.499947
-127.501846
-189.171385
0.499985
-127.501846
-189.171385
0.500022
-127.501846
-189.171385
0.500060
-127.501846
-189.171385
0.500098
-127.501846
-189.171385
0.500136
-127.500073
-189.171697
0.500174
-127.499578
-189.171784
0.500211
-127.499096
-189.171869
0.500249
-127.498601
-189.171957
0.500287
-127.498106
-189.172044
0.500325
-127.497610
-189.172131
0.500362
-127.497128
-189.172216
0.500400
-127.496633
-189.172303
Note the repeated values (-189.171385)
I constructed the same spline with python (see artifact.py) and get smooth results
u
x
y
0.499531
-127.507957
-189.170307
0.499569
-127.507462
-189.170394
0.499607
-127.506967
-189.170481
0.499644
-127.506484
-189.170566
0.499682
-127.505989
-189.170654
0.499720
-127.505494
-189.170741
0.499758
-127.504999
-189.170829
0.499796
-127.504504
-189.170916
0.499833
-127.504022
-189.171001
0.499871
-127.503526
-189.171088
0.499909
-127.503031
-189.171176
0.499947
-127.502536
-189.171263
0.499985
-127.502041
-189.171350
0.500022
-127.501559
-189.171435
0.500060
-127.501064
-189.171523
0.500098
-127.500568
-189.171610
0.500136
-127.500073
-189.171697
0.500174
-127.499578
-189.171784
0.500211
-127.499096
-189.171869
0.500249
-127.498601
-189.171957
0.500287
-127.498106
-189.172044
0.500325
-127.497610
-189.172131
0.500362
-127.497128
-189.172216
0.500400
-127.496633
-189.172303
You can see that the issue is only in the range where u is between 0.499909 and 0.500098, but otherwise all values match!
Here are the two scripts I used to find this issue:
I tried debugging myself, but got a bit lost when it came to the DeBoor algorithm. Hoping you can spot this relatively quickly!
Thanks again for the great library!
Jay
The text was updated successfully, but these errors were encountered:
Hello again!
I came across a pretty interesting issue where I am seeing artifacts around the center of a seven point spline.
The fifth-degree spline is formulated with seven control points. The details can be seen in the example scripts I've attached, but here is the symptom:
The x-axis on the plots are "time" - the spline is evaluated at each successive value every 1ms.
Anyway, the spline is moving along smoothly and then around
u = 0.5
, there is a discontinuity. This plot was generated using the artifact.c example. Here is the same data in table form:Note the repeated values (-189.171385)
I constructed the same spline with python (see artifact.py) and get smooth results
You can see that the issue is only in the range where u is between 0.499909 and 0.500098, but otherwise all values match!
Here are the two scripts I used to find this issue:
artifact.c
artifact.py
I tried debugging myself, but got a bit lost when it came to the DeBoor algorithm. Hoping you can spot this relatively quickly!
Thanks again for the great library!
Jay
The text was updated successfully, but these errors were encountered: