Analysis Workspace and Two-Epoch Comparison

You flew the same site two months apart; now you hold two orthophotos, maybe two 3D models. The real question is: "What changed, where, and by how much?" Flipping between two tabs will not answer it reliably. The CartaX Analysis workspace puts both dates into one scene: you drag the boundary between them, read the same measurement in both epochs, and calculate cut-fill from the difference of the two surfaces. The Analysis workspace is part of the Professional plan.

Adding assets to the analysis

The analysis does not see every layer in the project — only the ones you mark. The Analysis button (labelled Analiz) on an orthophoto or 3D model row in the layer panel adds that asset; clicking again removes it. For point clouds, use Add to analysis in the Point Clouds window.

A comparison needs three things:

• At least two assets of the same type — two orthophotos, two models or two point clouds
• The same site — for records whose extents do not overlap, the workspace warns: "The two selected epochs belong to different regions"
• A capture date — the timeline is ordered by it; a record without a date cannot be selected until you enter one on its card

When everything is in place, switch over with the Analysis workspace button in the assets drawer; Back to map brings you back.

Choosing the type and the epochs

In the bottom bar you first pick the comparison type: 3D model, point cloud or orthophoto. Only types with two compatible records can be clicked. Then you pick two epochs from the timeline cards: the first click fills the left side, the second the right; the workspace sorts records by date, so the older one is shown on the left and the newer on the right. Clicking the same card again clears it; when both sides are full, a new card replaces the right one.

Cards can be edited (name and date), and each card can carry attachments: a vector layer such as KML, DXF or Shapefile, or a 360 collection. With apply to all cards of this type an attachment is copied to the cards that lack it — the quickest way to see a fixed layer such as a parcel boundary in every epoch.

The sweeper view

Both epochs open in a single scene with a vertical sweeper between them. Drag the sweeper and the boundary moves: the older epoch to its left, the newer to its right. The camera is shared, so wherever you zoom you are looking at the same spot on both dates; labels in the scene tell you which side is which record. Saved measurements are visible on both sides of the boundary. In a point cloud comparison a point cloud quality check panel also reports coordinate system, vertical reference, overlap and density compatibility — and tells you not to trust height differences when the two clouds use different references.

Measurement tools

The tool set depends on the selected type:

Type	Tools
3D model	Line Measurement, Point, Area, Line of Sight, Cut-Fill
Orthophoto	Line Measurement, Area, Point
Point cloud	Distance, Area, Angle, Point Coordinate, Circle

What makes analysis different is that a measurement is read in both epochs at once. Draw a Line Measurement on an orthophoto or model and the elevation profiles of both epochs appear on a single chart; as you move the cursor you read both elevations and the ΔH between them. This needs a DSM/DTM in both epochs; otherwise the line gives horizontal distance only. In a point cloud, every point you click is resolved on both the A and the B surface, and the values are shown separately for each epoch. You name the measurement when saving, and the name appears on the label on both sides. The Measurements list handles renaming, hiding, styling, vertex editing and deleting; if a value cannot be recalculated for the selected pair, the row is marked as stale. The map tools themselves are covered in the measurement tools guide.

Cut-fill

The Cut-Fill tool in the 3D model comparison derives volume from the difference of the two epochs' elevation models: draw a polygon and finish with a right click — "Left = old DEM, right = new DEM." The result line reads Cut · Fill · Net · Samples; if part of the polygon falls outside the shared extent of the two models, the result is flagged as partial with a percentage. In the Settings panel of the bottom bar, the Measurement surface section lets you pick DSM, DTM or Model surface; the choice becomes available when both epochs carry both a DSM and a DTM. With the model surface selected, elevation, slope and profile values are sampled from the rendered model, while cut-fill continues to use the elevation model. For the sign convention, cell size and the DSM/DTM decision, see the volume calculation and DSM vs DTM guides.

Map panel, external layers and TKGM

The Map panel in the bottom bar opens in model and orthophoto modes. Pick Satellite or Carto as the Base map; in the Layers section, + WMS/WMTS layer adds an external service, each layer can be shown or hidden, and the Opacity slider drapes it semi-transparently over both epochs. The TKGM button turns on parcel query mode: click a point on the model and the TKGM Parcel window shows province/district, neighbourhood, block/parcel, land use, area and perimeter; the result is attached to every card. Details are in the TKGM parcel query guide.

Notes

You can leave a Note at a point in the scene and add it to any of your shares; a Share note goes straight to the guests of the active share. Guests see the notes, reply to them and drop pins of their own — the shortest route to discussing a changed corner with the client.

Sharing: the recipient lands directly in the A/B workspace

Choose analysis mode (live) in the sharing panel and create the analysis share link: the recipient enters their PIN and lands straight in the two-epoch workspace. This share is folder based — assets, measurements and attachments you add later flow into the link automatically — and it requires at least two analysis assets. Guests can measure, but their measurements are temporary and cleared on refresh. Analysis shares open in a desktop browser. Setup is covered in the PIN-protected sharing guide.

Three use cases

• Earthwork progress — add each month's model with its DTM to the analysis and draw a Cut-Fill polygon zone by zone; the net m³ goes straight into the progress claim.
• Stockpile change — with the DSM of both epochs, pull a Line Measurement across the pile; both reliefs sit on one chart, and a section that dropped or grew is read at a glance.
• Monthly construction comparison — sweep between two orthophotos, leave a Note on each change, and share the link with the client in analysis mode.

Frequently asked questions

Question	Answer
Why can't I pick a comparison type?	Fewer than two location-compatible assets of the same type have been added to the analysis
Which side is older?	The left; the workspace sorts by capture date
No profile chart?	Both epochs need a DSM/DTM; otherwise only horizontal distance
Is cut-fill available in orthophoto mode?	No — in the 3D model comparison
Can guests measure?	Yes, but temporarily; cleared on refresh
Does it open on a phone?	Analysis shares require a desktop browser