I'm looking on how to add attributes to a raster of points, based on their neighbors

It may be easier to do your calculations on the original raster. Have you looked at the Raster transformers?

Thank you for your reply. I have looked on how to do this with raster transformers, like the RasterSlopeCalculator, but it "only" gives the maximum rate of change in z in the cell, and I need to hav the slope for all 8 directions

Thank you fot your reply.

I'm not very familiar with lists. I know the values are like stored and can be called with {} but I don't really know how to retrieve them.

I had already tried the NeighborFinder (Candidates Only mode somhow only returns unmatched elements) but it's not very clear to me what happens

It now seems to work, thank you. I had an error in my formula @sqrt($(Resolution)^2 + $(Resolution)^2) * 1.1, as FME Arimthmetic Editor doesn't understand ^ as power, I have to write @sqrt(@pow($(Resolution),2) + @pow($(Resolution),2)) * 1.1 and everything works fine

Glad to see the NeighborFinder approach works for you. Below is some more explanation about the lists.

This is my dummy workspace:

These are the settings of my NeighborFinder:

As you can see under Attribute Accumulation, I collect all values from the Z attribute to the list called _NeighborList.

You can explode the list with the ListExploder, which results in this:The ListExploder basically multiplies your input features with the amount of list elements. I have prefixed the neighbor attributes with nb_ to avoid confusion. 'Z' and 'ID' are from the original point and 'nb_Z' and 'nb_ID' are from the neighboring points.

As you can see, ID 1 has three neighbors, so three points are generated. These points have the attributes of ID 1 (Z = 3.9) and of the neighbor points ID 2, ID 11, ID 12 (nb_Z = 2.6, nb_Z = 3.2 and nb_Z = 1.3).

You can do further calculations with these exploded features and e.g. merge it back together based on the original ID.

Have fun!

Worked perfectly for me, thanks!