Coordinate grid, points grid and the British grid

What it does

CAPCAD_GEO_GRID opens the Coordinate grid: you select one or more closed boundaries and the command draws, inside each of them, the grid lines at multiples of the chosen spacing, with the coordinate labels along the edges. Every change of parameter rebuilds the grid over the same boundaries, erasing the previous one — which is what makes the form feel like a previewer. In paper space, the boundaries can be the viewports themselves.

CAPCAD_GEO_GRID_POINT opens the Points Grid: inside a closed boundary, a regular grid of POINTs at the chosen spacing, optionally with the Bing Maps elevation in Z — the quick base for an approximate surface, or for checking the relief of a stretch.

CAPCAD_POINT_TO_COGO converts POINTs, attributed blocks or text in the drawing into Civil 3D COGO points, gathered into a point group, with the raw description taken from the attribute, the text or the layer name.

CAPCAD_GEO_UK_OS_TILE and CAPCAD_GEO_UK_BOUNDARY are the two British utilities: the first reads the Ordnance Survey grid reference of every point you click; the second draws the outline of the United Kingdom in BNG — not available in this version; see the Notes.

Everything involving a conversion depends on the drawing's coordinate system — see Coordinates and the coordinate system, and in particular What actually converts.

Workflow

Drawing the coordinate grid

1. Run CAPCAD_GEO_GRID.
2. Set the Space (11) and, if you want, the style (12/13), the text height (6) and the prefixes (2, 3 — the XY (4) and EN (5) buttons fill in the two usual pairs).
3. Click Select boundaries (16). The form hides, you select the closed boundaries in the drawing, and the grid appears.
4. From then on, any change to the controls redraws the grid over the same boundaries. The footer reports how many lines and how many labels were drawn, over how many boundaries.
5. Reset (17) erases the grid and forgets the selection; Update (18) forces a redraw.

In paper space, choose the mode on the Options tab first (28 to 32): step 3 then asks for viewports instead of boundaries, or asks for nothing at all in All viewports mode.

Creating the points grid

1. Run CAPCAD_GEO_GRID_POINT.
2. Give the Spacing (35) and decide whether you want the elevations (34).
3. Click Create points grid (36) and select the boundary. It must be closed; if it has arcs, the command asks whether to ignore them, tessellate (splitting each arc into 10 chords, and drawing the result) or cancel.
4. Without elevations, the points are drawn at once, on the current layer, with Z = 0.
5. With elevations, the command asks for the coordinate system (if there is not one yet), says how many points it will process and asks for confirmation, queries Bing Maps in batches of 100 points and draws 3D points on layer CAPCAD_GEO_POINTS.

Converting points into COGO points

1. Open the drawing in Civil 3D and run CAPCAD_POINT_TO_COGO (or the COGO point conversion… button of the Civil 3D utilities).
2. In the form, choose the data source: POINT entities, attributed block (INSERT), or TEXT / MTEXT.
3. With a block: click Selecionar bloco…, pick an instance in the drawing, and the attribute combo boxes fill with its tags.
4. Set the elevation (from the entity's Z, fixed, or forced to zero), the raw description and the point group name.
5. Converter. The command asks for the selection, already filtered by the chosen type, creates the COGO points, builds the group and — if you ticked it — erases the original entities.

Reading the OS grid reference

1. With the drawing in BNG, run CAPCAD_GEO_UK_OS_TILE.
2. Click a point. The 500 m tile reference appears in a box and is copied to the clipboard.
3. The command keeps asking for points until you press Esc.

The forms

The numbers are unique on this page: 1 to 33 in the Coordinate grid and 34 to 36 in the Points Grid. All the captures are of a Portuguese session; the numbering is the same in both editions, and the tables give the English captions.

Coordinate grid — CAPCAD_GEO_GRID

The eight footer controls (11 to 18) sit below the tabs and appear on all of them.

Tab 1: Text

Factory defaults: spacing 100, continuous style, text on all four sides, height 2.

Tab 2: Text options

Tab 3: Layers

Both names are also what the tools on the next tab act on.

Tab 4: Tools

Tab 5: Options

The Paper space frame is only active while you are on a layout; in model space it is disabled and its caption says why.

Careful. The five radio buttons 28 to 32 sit in the same frame and therefore form one single exclusive group: choosing Paper unticks the viewport selection mode, and choosing a viewport mode unticks Model / Paper. In this version you cannot combine, say, All viewports with Paper. See Notes.

Points Grid — CAPCAD_GEO_GRID_POINT

Converter em Pontos COGO — CAPCAD_POINT_TO_COGO

There is no screenshot of this form on this page. It shows Portuguese captions — everything below is quoted in Portuguese, as the form shows it, with a gloss. The controls, in five frames:

The Converter button validates before closing: the fixed elevation and the tolerance have to be numbers, the group name cannot be empty, and the Bloco source requires that a block has already been selected.

How the options combine

How the grid is built

The command does not draw a lattice over the boundary: it clips. For each ordinate at a multiple of the spacing, an infinite line is intersected with the boundary, the intersections are sorted along the axis and paired two by two — each pair is a stretch on the inside. That is where the correct behaviour on concave boundaries and boundaries with islands comes from: a line crossing the "mouth" of a C-shaped boundary gets two segments, not one.

The first ordinate is the first multiple of the spacing strictly above the bottom (or left) side of the bounding box. The two axes are not symmetrical: the top line can be missing where the right-hand column appears.

When each label is drawn

The length of the stretch decides, and the thresholds are asymmetrical:

So a short stretch (between 20 and 40) gets exactly one label — the right-hand or the bottom one. Each label is then shifted along its own axis by height × 1.333 × cot(θ) (or tan(θ) on the verticals), θ being the boundary's direction at the crossing, so that it does not collide with a sloping edge.

What the style and the line boxes combine to

The points grid and Bing Maps

The grid starts at the integer floor of the bounding box's lower-left corner and advances by the spacing on both axes, keeping only the nodes that fall inside the boundary. With the elevations switched on, the points are reprojected to latitude/longitude and sent to Bing Maps in batches of 100, with progress on the command line. A reprojection or network failure aborts the whole run — not even the points already processed are drawn. The 3D points come out on layer CAPCAD_GEO_POINTS, ACI colour 8.

The Ordnance Survey grid reference

CAPCAD_GEO_UK_OS_TILE treats the clicked point's coordinates as if they already were British National Grid easting and northing: there is no conversion at all. The reference returned is that of the 500 m tile — two letters, four digits and the quadrant suffix (NE, NW, SE, SW). A point outside the letter grid returns "Outside the OS grid."

Remembered between sessions

The Points Grid keeps the elevation box and the spacing. The Coordinate grid keeps nothing: every opening reloads the factory defaults listed in the tables above. The Converter em Pontos COGO form keeps nothing either: it always opens at the factory defaults.

Notes

• CAPCAD_GEO_UK_BOUNDARY is not available in this version. The run stops with the message "BNG conversion failed". The same happens in every GIS command in which you choose BNG in the coordinate-system box — and BNG is what the United Kingdom profile hands out as its default when nothing else is set.
• The coordinate-system box offers more than it converts. WGS-84, BNG and the 120 zones UTM-01S to UTM-60N appear in the list, but only SIRGAS 2000 and SAD 69 over zones 17 to 25 South and 11 to 22 North are actually resolved. That is why the Latitude / longitude (DMS) box (21) is disabled in drawings outside that coverage: the form tests the conversion of a sample point on opening and, if it fails, switches the option off and says so on the command line. It is also disabled when there is no coordinate system set, and when the system is WGS-84 — the drawing is already in degrees then.
• In latitude/longitude mode, all four sides show the LATITUDE. The top and bottom labels — the X axis — show the latitude too, not the longitude. If you need the longitude, label in projected coordinates.
• The paper-space modes do not combine. The five radio buttons on the Options tab (28 to 32) share a single group, so Select viewport(s) / Viewport and ref. polyline / All viewports and Model / Paper cancel each other out. On opening the form, the effective default ends up being Model with no viewport mode ticked.
• A north arrow and a text-style selector are not available in this version. The text comes out in the drawing's current style.
• A boundary that is not closed produces no points grid. CAPCAD_GEO_GRID_POINT refuses open geometry with a message saying it must be closed. A boundary with arcs asks first: ignore and continue, cancel, or tessellate — tessellation splits each arc into 10 chords and draws the tessellated curve in the drawing.
• Without elevations, the points grid ignores the CAPCAD_GEO_POINTS layer. The points go onto the current layer; only the elevation path creates and uses the dedicated layer.
• The OS reference is only reliable with six-digit values. The reference's four digits are cut from positions 2 and 3 of the easting and the northing written as text. Coordinates with fewer than six integer digits produce a reference shifted by one place. The command also always uses the 500 m tile.
• CAPCAD_POINT_TO_COGO requires AutoCAD Civil 3D — not just AutoCAD — and does not exist on the other four CADs.
• The COGO form's numbering never reaches the point created. Número inicial, Prefixo, Sufixo and the number attribute are only used to build the labels in the duplicate-check messages; the COGO point's number is whatever Civil 3D assigns on creation. The point group, on the other hand, is built with the real numbers.
• The duplicate-number confirmation does not list the numbers. When the command detects repeated numbers, the confirmation box asks whether to continue — Yes carries on discarding the duplicates, No cancels — but the text does not say which numbers collided.
• The duplicate-XY check is slow on large selections. It compares every pair in the selection; on very large selections the command visibly stalls between the selection and the creation of the points. Untick Avisar sobre coordenadas XY duplicadas if you do not need it.
• Bing Maps is an external service. The points grid with elevations depends on the network and on the elevation service answering; any error is reported and the run is abandoned.