How is model comparison made for diffing in the new web application?

Hi Dimitrie,

Thanks for addressing my question in the stand up. Just for reference, I’m copying the original question below:

In the versions comparison, is the comparison done by element id? I would like to compare two models of the same building that were created separately (i.e. one version is not an “edit” of the original version, but rather a new model of the same building)

Basically, we were using a survey model of an existing building, but then received a new survey model (completely new) of the same building, and I would like to find the differences between these two models (as I have noticed some elements missing between the two, and would also like to highlight slight differences).

I had sent each of these models to separate streams, but I didn’t see how to load the models into the project from these streams (I must be missing something basic?!), so, instead, I exported the Revit models to IFC and tried loading those into a project.

Thanks very much in advance!


Thanks for following up Mia! I’ve added Benjamin and Jonathon to this conversation to keep track of this request.

There’s clearly some terminology and product confusion which is on us (different topic).

Based on what you explained to me here, we might not support this out of the box: Two different Revit models, even if of the same building, will most likely have different element ids for the conceptually “same” entity, and this means our diffing algorithm will not pick things up easily :cry:

Hi Dimitrie,

Totally understandable, I sort of figured this would be the case, no worries! I’ve taken a deeper dive into the models, basically using schedules to compare elements in the models more closely. It seems that there are some elements with the same Id in both models, but still a lot of differences. I’m thinking of maybe using a combination of these schedules in powerBI alongside the speckle 3d viewer to try to highlight differences. If I manage, I’ll share here :slight_smile: Just to say, speckle is powerful either way!

Thanks again!



I just thought I would drop a brief update, as I mentioned in my previous message.
Since I had noticed that there seemed to be some shared elements between the two models, I thought I would test out the model compare by first sending the original survey model to a new stream, and then subsequently sending the new survey model to the same stream.

This seemed to work, in that it seemed to at least pick up a few of the differences that I’m aware of (fire escape stairs on the exterior of the building exist in the original model, but not in the new model; interior walls that exist in the original but not in the new). Very exciting!
This is the link to the project:

Before doing this, I was working on using separate speckle streams to try to identify and visualize the differences between the models in PowerBI.
This is very much just a test/WIP, but aims to identify the elements that are unique to each model (old and new): model-comparison

While I’m not 100% sure that either method captures all of the differences accurately, I think that comparing the results of the two methods at least gives some confidence in both tools. Thank you Speckle!! <3


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Thanks @evthymia ! Keep the feedback coming.