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Compare and merge

Copying a project is how you explore an alternative without risk; comparing is how you get the good parts of that exploration back. The Compare / Merge tool diffs two projects that describe the same site, shows every input difference — facilities, layers, criteria, relationship groups, relationship edits, saved result sets, to-dos — and applies the changes you select into a recipient project. It closes the loop that Copy opens: copy, experiment, compare, merge back what worked. For the click-by-click flow, see Comparing and merging projects.

Learning objectives

By the end of this lesson you should be able to:

  • Pick the right source and recipient for a merge
  • Read the comparison sections and their add / update / only-in-recipient rows
  • Narrow a long facility list by layer without losing selections
  • Explain why face-related changes merge as a group and why faces are rebuilt rather than copied
  • Predict how to-do items and their facility links travel through a merge
  • Predict which differences the tool will and will not surface
  • Apply a partial merge safely, keeping deletions explicit

Direction matters: source → recipient​

A comparison always has a source and a recipient, and selected changes flow one way: into the recipient. The same two projects produce mirror-image readings depending on direction — a facility added in your working copy reads as an addition when the copy is the source, and as an only-in-recipient row when the direction is swapped. Before selecting anything, check the banner and ask: which project should end up changed? That one is the recipient. Use the swap button if it's backwards.

What the comparison covers​

The tool compares the project's inputs, plus saved result sets, grouped into eight sections:

SectionWhat's diffed
FacilitiesAdded/removed facilities and per-field updates: name, Facility Description, Notes, and Submittal Notes (three separate rows, merged independently), layer, front side, shape, categories, attributes, explosives, faces. A Layers drop-down at the top of the section hides layers you are not reviewing
LayersFacility layers that exist only in the recipient, offered for deletion (Keep by default)
Project CriteriaCriteria standards present in one project but not the other
Relationship GroupsGroups added/removed, priorities, matrix values, and facility assignments
User Relationship EditsManually overridden relationships and barricade links
Relationship NotesRelationship notes added, edited, or only in the recipient, one row per PES → ES direction with the old and new text. An edit replaces the recipient's note, an add creates it, and a recipient-only note can be deleted without touching the opposite direction
Result SetsSaved result sets: source-only sets to add, sets in both projects (Don't merge / Overwrite / Add as copy), and recipient-only sets to keep or delete
To-do ItemsAdded and changed to-do items, with their facility links; recipient-only to-dos are listed for reference and never deleted

Everything else — live analysis results, build-generated relationships, decorations, project settings, users and sharing — is out of scope by design. A merge changes what you put into a project, never what Siter calculated from it; re-run analysis (and rebuild relationships, which Siter offers when relevant) after merging. Result sets are the one snapshot the tool does carry across, and it treats them as snapshots: a set merges whole or not at all, matched to the recipient's sets by copy lineage first and then by name, and the confirmation dialog reminds you that a merged set is the source's analysis, not a fresh one of the recipient.

Faces are rebuilt, not copied​

A facility's faces are generated from its category codes, shape, and front side, so the tool never copies face geometry from the source. Changes to Cat, Shape, Front Side, and Facility faces on one facility are linked — each row names the others, and selecting or deselecting one does the same to the group. On merge, Siter rebuilds the faces in the recipient using the recipient's criteria search distances, carrying over the front side, custom face definitions, and barricade flags. Two consequences worth teaching: face differences caused only by the two projects using different search distances are ignored, and a Cat justification row stays independent because it changes text, not segmentation.

To-dos travel with their facilities​

A to-do item's link to its facility survives the merge whenever the facility does: the link is kept when the facility is already matched in the recipient, or is added by the same merge. When the facility is not in the recipient, the comparison warns up front, and the to-do arrives unlinked but keeps the facility's name — the To-Do list marks it as not linked, and merging the facility later and re-running the merge restores the link. To-dos themselves are matched between the projects in staged passes — copy lineage first, then facility link and note, then note text alone — so similarly-worded to-dos cannot pair up wrongly, and a pairing made on note text alone is never trusted to move an existing facility link. Points worth teaching:

  • Merging never deletes recipient-only to-dos — but deleting a facility deletes the to-dos attached to it, the tool warns with a count, and that (like all to-do changes) cannot be undone
  • The post-merge notifications distinguish to-dos deleted with a facility, merged without their link, and left with their current link — each names the to-dos affected

How facilities are paired​

The tool matches facilities between the projects automatically. Copies carry an exact lineage link, so a copy compared to its source pairs cleanly even after renames and moves. Facilities without lineage are paired by name and shape similarity and flagged with a Likely match badge — review those pairs, and use break match on any that are wrong. A broken pair becomes an addition on one side and an only-in-recipient row on the other.

Deletions are always explicit​

Select All never deletes anything. Rows that exist only in the recipient default to Keep, and each must be switched to Delete individually. A recipient-only layer goes one step further: because deleting a layer deletes every facility on it, its Delete is locked until the facility deletions and layer moves you have selected would leave it empty, and it falls back to Keep if you later deselect one of those. The confirmation dialog lists every deletion before the merge runs. Almost everything a merge does can be reversed from the map with Undo — the exceptions are to-do and result-set changes, which the dialog calls out.

When a filter hides part of the Facilities list, Select All and the section checkbox act only on the rows you can see; anything already selected on a hidden layer still merges, and the tool says how many such rows there are.

When compare/merge beats the alternatives​

  • Copy experiments — merge a successful what-if back into the baseline instead of redoing the edits by hand
  • Parallel edits — two people worked in separate copies; compare each against the baseline and merge selectively
  • Reviewing a copy's drift — even with no intent to merge, the comparison is a readable change list of everything a copy has diverged from its source

For moving a whole project between environments, export and import remains the right tool — compare/merge moves differences, not projects.

Try it​

  1. Copy a project you can experiment in (see Copy)
  2. In the copy: rename a facility, move one, change an explosive weight, add a facility, delete another, and save a result set
  3. From the Project Management page, select the copy and the source and click Compare / Merge
  4. Make the copy the source and read each section — find your edits, then expand the added facility's preview and open the shape-change panel for the move
  5. Tick the Shape row for the moved facility and note that its Facility faces row selects with it; untick one and watch both clear
  6. Use the Layers drop-down to hide every layer but the one you edited, then click Select All and confirm only the visible rows were selected
  7. Show all layers again, select everything except the deletion, set the deleted facility's row to Keep, tick the added result set, and merge
  8. Confirm the source project gained your edits and the result set but still has the facility you deleted from the copy — then undo the merge from the map and note that the result set stays