Tutorials CivilCraft help Walkthroughs
Analyze GIS layers
Buffer, overlay (intersect, union, erase, dissolve), spatial join, select by attribute and measure the GIS layers in a project, each as a new layer you can undo.
Written for CivilCraft 0.9. The same help is inside the app: press F1.
Once a project has GIS layers (see Import GIS data), the Analyze button in the GIS group (typed GISANALYSIS, ANALYZE or BUFFER) opens a panel with five tabs. It stays open beside the plan, so what you select is drawn on the plan while you work.
Every tool that makes something adds a new layer and leaves the layers it read exactly as they were. Each is one undo step: Undo in the panel (or Ctrl+Z) removes the new layer. Export the result like any layer with Export as-built data for GIS as a shapefile, GeoJSON or GeoPackage.
The full table of a layer, with sorting, editing and a field calculator, is in Work with a layer's attribute table; colouring by a field is in Style a layer by an attribute.
Everything is worked in the plan, in the project's units (feet or meters). A project is always in a projected or local system, so a distance of 50 means 50 feet or 50 meters, never degrees. Heights (z) are not kept in the results.
Buffer
Draws a zone of a set distance around every feature, as a new polygon layer. Points become circles, lines become corridors with rounded ends, polygons grow. A negative distance shrinks polygons (a 100 by 100 square shrunk by 5 is 90 by 90; shrunk by 60 there is nothing left, and the panel says so). Take the distance from a number field to give each feature its own, or tick Merge all the buffers into one shape to dissolve them.
The rounded parts are straight pieces drawn inside the true curve, so a buffer is a hair smaller than the exact circle: about 0.6 % in area at the normal setting, 0.16 % at Fine. Use Fine for anything you will measure.
Overlay
| Tool | What you get |
|---|---|
| Intersect | The pieces where the input layer meets the overlay polygons, each with the fields of both. Lines and points are clipped to the polygons. |
| Union | Both polygon layers cut along each other's edges: shared pieces carry both layers' fields, the rest carry one layer's (the other's fields are empty). |
| Erase | The input polygons with the overlay polygons taken out. Fields stay with the input. A feature erased completely is left out (the panel counts them). |
| Dissolve | Merges polygons that touch or overlap, all of them or one shape for each value of a field. Adds COUNT and AREA. |
A field name that both layers have is kept for the first layer, and the second layer's is written with _2. Features inside one layer should not overlap each other: where they do, a Union counts the overlap in both.
Join
A spatial join copies attributes from a source layer onto each target feature that meets it, and gives a new layer with the target's shapes. Choose when they meet: touching or overlapping, the target lying inside a source polygon, the target holding the source feature, the nearest source feature (with an optional limit), or any source feature within a distance.
When several source features match you take the first one's attributes (the nearest, for nearest and distance joins; DISTANCE is added), or count them and total their number fields: COUNT, and SUM_, MEAN_, MIN_, MAX_ for each number field. Untick Keep target features that found no match to leave those out. Joined fields are empty where nothing matched, and the panel counts the unmatched.
Select
Type a question about the attributes or the shape, press Select, and the features are drawn on the plan with their count, a table and the total area, length or number. Then make them a layer of their own, zoom to them or clear the selection.
| You can write | Example |
|---|---|
| A field by name; use "quotes" or [brackets] if the name has spaces | VALUE, "Lot Number" |
| Numbers, 'text', true, false, null | Use_ = 'Res' |
= != <> < <= > >= | VALUE >= 250 |
contains startswith endswith like ilike (text ignores case; in like, % is any run and _ one letter) | Notes contains 'corner' |
is null, is not null (an empty value counts as null) | Notes is null |
in (…), not in (…), between … and … | Use_ in ('Com', 'Ind') |
+ - * / and brackets | VALUE / 2 > 100 |
and, or, not | Use_ = 'Res' and VALUE > 200 |
Shape values $area $perimeter $length $x $y $vertices | $area > 5000 |
A question that is incomplete or names a field the layer does not have is refused with a sentence that says where.
Measure
Shows the total area and perimeter, length or number of the layer, and adds fields to it: AREA and PERIMETER for polygons, LENGTH for lines (the plan length), X and Y for points. A field that exists already is never overwritten: the new one is called AREA_2. This is one undo step. Statistics gives the count, sum, mean, minimum and maximum of a number field, optionally for each value of another field.