I have a 3D dataset consisting of xyz and property. The data points are along vertical axis (boreholes), and at different XY locations (at other borehole location). The data points are not all at the same elevation between each borehole location due to different soil intervals, and the property value is only provided for the Top of the interval.

My goal is to populate the borehole with properties between different soil Tops of interval, so that I can map properties at different horizontal elevation slices.

I found how to do this with Cross Join Query in MS Access but this creates very large data sets which can make the software crash as it provides every permutation possible.

Once that is done, the data needs to be filtered. So I am wondering if in QGIS, if there is a way to do something similar without having to generate this huge dataset by a Cross Join query. For example it would resemble something like this in plain english: "show points at elevation 110 masl at each Borehole location, if no point at elevation 110, then pick next one up."

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    welcome to gis.stackexchange! Can you edit your question to include a more detailed description of your data, what operations you performed with them, what was the result obtained and what was the result you intended to obtain? Also, clarify: + What are the "properties" of the points? + Do these have the Z component stored in their geometry or in a field of their attribute table? + What is the criterion to define each elevation slice? – Gabriel De Luca Mar 8 at 1:09
  • It doesn't sound like you have 3D data, only 2D data with some height attributes, 3D data you would have coordinates like x1,y1,z1, – nmtoken Mar 8 at 18:13

I solved this by doing a cartesian join directly from MS Access and reimporting the data into GIS.

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