Congrats! Simpeg is amazing! I just started using Simpeg. I have a question about Gravity tutorial Forward Simulation of Gravity Anomaly Data on a Tensor Mesh (Forward Simulation of Gravity Anomaly Data on a Tensor Mesh — SimPEG 0.14.3 documentation).

Why in “Simulation: Gravity Anomaly Data on Tensor Mesh”, in the example, have negative mgal anomalies related to sphere positive density body 0.2 g/cc and positive mgal anomalies related to block negative density -0.2 g/cc. It wouldn´t be the opposite??

Thanks!

Hi @Marcelo,

SimPEG is consistent with having a Z-up positive convention for all methods (the Z-axis points up).

Example: A body with a positive density-contrast produces more pull, consequently its vector gravity anomaly is pointing down. Thus it produces a negative anomaly in that convention (which is, indeed, the reverse of the usual convention for gravity).

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