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I am create IDW interpolation of 60-70 points in ArcGIS. It takes 2 minutes. But when I create IDW of 20000 points in ArcGIS, it takes at least 4 hours and 30 minutes. I want to ask why takes much time for 20000 points for IDW interpolation.

  • There's an "N-squared law" that applies here, so it's certain that 20k points will be significantly longer to process than 70. In fact, the increase in processing time is nearly uniform, so it's clear that optimization is taking place. Are you asking what the IDW algorithm is? – Vince May 20 '19 at 14:37
  • If you clarify your question to have it reopened please include additional information on your analysis. It strikes me that the grain and extent of the interpolation would effect run-times even more than number of points. You do not provide any information on this. I have run much larger IDW models >500k and have not had anywhere near these processing times. Are the extents and cell size the same between the two IDW's? If you are attempting high resolution over large extents, expect it to take time. – Jeffrey Evans May 20 '19 at 15:42