I've been wondering why and how I should utilise the instance node.
I was following a tutorial which uses the instance node to create multiple geometry (using a string ‘instance’ (leading to the geo path) attributes per point inside the node) across terrain however the point instancing method he suggest (fast point instancing) doesn't seem to render in mantra (Outputs error: “mantra: ptinstance couldn't find object ‘/geo2’”).
Whereas full point rendering seems to do the trick and gives me the result I'm satisfied with.

I also read the info of the node "https://www.sidefx.com/docs/houdini/nodes/obj/instance.html [www.sidefx.com]" which talks about the speed of IFDs/RIBs and export times but with houdini Indi I cant even archive IFD (using ifdarchive node (also suggests in documents to use “Archive Generator (render node)” but the node is not available anywhere)) in the OUT space.

However this can be similarly achieved using the copy to point sop and packing the geometry with UV and material path if there are textures.

So all in all I am wondering Why should I used this instance node over the copy to point sop and How is fast point and full point different.

Example files would be much appreciated to explain the difference.
Thank you in advance

The main benefit of the instance node is efficiency in Houdini workflow. Copy to points or copystamp has to cook and display in the viewport which can seriously slow down your workflow if you have alot of geometry to generate. Instance generates the geometry at render time. Fast point instancing is for geometry and full point is for lights (at least thats how I've learned it).

I have an example attached where I get up a wheat field using instancing which generates about 2 billion polygons (could be lowered and more efficient if I had set up levels of detail but its an old project).

There is also an example of full point instancing with lights from my professor. This is the link to her page with an explanation and an example file. https://www.deborahrfowler.com/HoudiniResources/Lights-Instanced.html [www.deborahrfowler.com]

Cheers mate, much appreciated.

However wouldn't copying to point a packed object negate the cooking of the object as it is packed?

Packed Primitives express a procedure to generate geometry at render time

-https://www.sidefx.com/docs/houdini/nodes/sop/pack.html [www.sidefx.com]

Also with the full point and fast point topic I watched and looked through the links attached on your post and in the hip file but all of them just state that this is just the way and don't go in further detail as to why we use it and when we use it.
Deborah just says use full point for light and fast point for object and doesn't explain it any further.
And in this video https://vimeo.com/52551778 [vimeo.com]commented in the hip file Scott Keating just says this is the preferred method and doesn't go into the technicalities of why this is the preferred method.

Again. Thanks for helping

No problem. Yeah the “thats just the way it is” explanation is about as far I know about which instancing to use as well.

With instancing you dont have to pack, there you can access attributes without having to unpack later if you need them, I suppose. I've used both but for very large amount of copies I use instancing. But also a thing to note with instancing as per my file (which I linked to the tutorial I referenced) you can use vops to easily randomize things like orientation, scale, etc. without stamp expressions and it can be changed with alot of flexibility. That's why sometimes i'll even use it for smaller scenes. If I want a lot things to be random about each copy it is much easier.

Fast point and full point might just be how the instanced geometry is rendered.
I guess you are just meant to do some trial and error to see which renderer accepts what type of point instance.
https://rmanwiki.pixar.com/display/RfH/Instances [rmanwiki.pixar.com] Here is a link to Rendermans page stating that the setting it to ‘Fast Point’ will

emit RenderMan ObjectInstance

and

Full point instancing or Off for Point instancing, it will not create instances but copies of the object instead

.

Who knows aye hahaha

Then there is the LOP's instanter for creating USD's to use that Karma(beta). Which makes the fast point and full point topic redundant.