I would not use SPS for something like this. You could do this,
Simba Code:
SomeTPA := minimap.getDots(MM_DOT_NPC,minimap.getBounds());
Mouse(middleTPA(someTPA));
From the image it looks like there is always that wizard npc there. This will find his dot and click on it, thus moving you to the altar. You might want to randomize that mouse though. But this is a workable idea.
You could also just search the minimap for that gray color of "island" the altar is on. It would find the altar island and all the smaller surrounding ones. You could break the findings into an ATPA and sort it by size. Like so,
Simba Code:
findColorsSpiralTolerance(x, y, TPA, GRAY_COLOUR, minimap.getBounds(), GRAY_TOL, colorSetting(2, GRAY_HUE, GRAY_SAT));
if (Length(TPA) < 1) then
begin
writeLn('Gray colour not found');
Exit;
end;
ATPA := TPA.toATPA(45, 45); // you would have to play with this line a bit
ATPA.sortBysize(true);
Mouse(middleTPA(ATPA[0]));
You could probably get away with using a DTM of the altar. Which would be by far the easiest method. Like so,
These are not ready to go solutions but ideas. I would use one of these three methods to do this.