Survey Terrain Tools for Blender

Terrain-focused modeling and measurement toolkit for fast survey/CAD-style mesh workflows.

Designed for production use: deterministic tools, world-space measurements, and predictable geometry creation.

Why This Add-on

• Hidden-vertex alignment with Align Hidden Verts to Plane (Z)
• Cursor-driven edge creation and controlled vertex sliding
• Slope workflows for single edits, line batches, and perpendicular extrusions
• Slope annotation labels and drop-direction arrows (Annotate Slopes)
• Practical circle-sector construction (2-point and true 3-point)
• World-space measurement tools (length, area, volume) and face-plane intersection edges in one panel
• Minimal setup, no external Python dependencies

Feature Overview Align

• Align Hidden Verts to Plane (Z)
• 2 verts: computes Z from a vertical-plane rule in XY
• 3 verts: projects hidden vertices along Z to the infinite plane defined by the 3 selected verts
• Workflow: hide vertices you want to align, keep reference vertices visible and selected, then run the operator
• Useful when pulling geometry in XY first (for example from ortho/reference edges) and resolving final Z/slope afterward

Faces

• Add Face Intersection Edges
• Edit Mode: select two or more faces (adjacency not required)
• For each pair of faces, intersects their supporting planes and adds one edge along the overlap clipped to both faces; faces are not deleted
• Works best on convex faces; concave ngons may miss segments or clip incorrectly

Cursor Edge / Slide

• Draw Edge Toward Cursor
• Modal viewport tool with preview line
• Works in Edit Mode from active/selected vertex
• Uses panel values: Use Fixed Length + Fixed Length
• Enables line creation at arbitrary mouse-defined angle with precise length control
• Creates one new vertex and one connecting edge on confirm
• Slide Verts Along Edges
• Slides selected vertices along exactly one connected visible edge
• Uses dedicated panel values: Slide Length and optional Planar (XY) (world XY projection / plan view)
• Default: exact slide distance along the 3D edge (world-space length)
• With Planar (XY): Slide Length is the length of the world XY projection of the move (still along the 3D edge); purely vertical-in-XY edges are skipped
• Ignores hidden edges when checking connectivity
• Vertices that do not match the one-edge rule are skipped

Slopes & Perpendicular

• Set Slope
• 2 selected vertices, applies Z offset on active vert from current slope inputs
• Set Slope on Line
• Batch tool: supports isolated selected edges or one connected open line
• Extrude Vertices ⊥ Planar (mesh XY)
• Extrudes selected vertices along the angle bisector (miter) of connected edges
• Builds offset line from the selected line/loop with adjustable slope on created edges
• Planar (mesh XY): edge directions are projected to local XY (plan view in mesh space); slope “run” is distance in that plane (not world-ground unless the object is aligned)
• Angle Correct Length compensates corner angles so offset width stays more uniform at bends
• Extrude Vertices ⊥ Fill Planar (mesh XY)
• Same as above, plus side-face fill between neighboring extrusions
• Supports one open non-branching line and one closed non-branching loop
• Extrude Vertices ⊥ Fill (Slope Range) Planar (mesh XY)
• Like Extrude Vertices ⊥ Fill, but slope varies linearly from Slope from (%) to Slope to (%) along the line
• Requires one open non-branching line (exactly 2 endpoints); no loop
• Active endpoint gets Slope to; opposite endpoint gets Slope from
• Dialog: Slope from (%), Slope to (%), Swap From/To (swap from/to in computation)
• Get Slope
• Reads slope from 2 selected vertices and writes result below the button
• Annotate Slopes
• Creates slope text + drop-direction arrows at edge midpoints (in a new collection)
• Processes all mesh edges (with optional length filter in dialog)
• Label format selectable in operator dialog: Percent (%) or Ratio (1:x)

Circles

• Create Circle Sector
• 2 verts: arc between selected endpoints using Radius (World)
• When distance > 2R, radius is remapped internally for computation only, major arc is used, and side is flipped internally for stable behavior
• Default is 3D (tilted arc plane). Enable Planar (XY) to force plan-view arc generation in world XY
• Tilt can be entered as Percent (%) or Angle (deg) (synchronized); ignored in 3-vertex mode
• 3 verts: true 3D circle from all selected points; generated arc passes through all three selected vertices
• Vertex Spacing (World) controls tessellation density

Measure (World Space)

• Length selected Edges (World)
• Length selected Edges (World) Planar (XY) — sum of edge lengths in world XY (plan view; vertical-in-XY edges contribute 0)
• Angle 2 Selected Edges (World) — smaller angle between two selected edges as lines in 3D (world); adjacency not required
• Angle 2 Selected Edges (World) Planar (XY) — smaller angle after projecting both edges to world XY (plan view)
• Area selected Faces (World)
• Area selected Faces (World) Planar (XY) — sum of face areas projected onto world XY (plan view)
• Volume (Selected Solid)

Results are shown directly in UI and suitable for quick iterative checks.

UI Location

3D Viewport -> N Panel -> Survey -> Survey Terrain Tools

Sections:
1. Align
2. Faces
3. Cursor Edge
4. Slopes and Perpendicular
5. Circles
6. Measure

Installation

1. Open Blender (5.0+).
2. Go to Edit -> Preferences -> Get Extensions -> arrow in the upper right corner → Install from Disk.
3. Select the ZIP file and Click Install from Disk.

Requirements

• Blender 5.0.0+
• No external Python packages

Support

• Email: jan.holinka@seznam.cz

License

GPL-3.0-or-later

Version

Current version: 1.1.0
Detailed history: CHANGELOG.md

Survey Terrain Tools - User Manual

Version: 1.1.0
Blender: 5.0.0+

---

Overview

Survey Terrain Tools provides terrain-focused modeling and measurement tools in one panel.

Panel location:

3D Viewport -> N panel -> Survey -> Survey Terrain Tools

---

Align Align Hidden Verts to Plane (Z)

• 2 verts: computes Z from a vertical-plane rule in XY
• 3 verts: projects hidden vertices along Z to the infinite plane defined by 3 selected verts
• Typical workflow: hide vertices to align, keep reference verts visible+selected, run operator

---

Faces Add Face Intersection Edges

• Edit Mode, two or more faces selected (they do not need to share an edge or vertex)
• For every pair of selected faces, builds the line where their planes meet and adds a new edge along the part that lies on both faces (in the mesh)
• Faces are left unchanged (no deletion); only new vertices/edges may appear
• Most reliable on convex faces; concave ngons can produce wrong or missing segments

---

Cursor Edge / Slide Draw Edge Toward Cursor

• Modal viewport tool with preview line
• Works in Edit Mode from active/selected vertex
• Uses panel values: Use Fixed Length + Fixed Length
• Supports arbitrary mouse-defined angle with precise length control
• Creates one new vertex and one connecting edge on confirm

Slide Verts Along Edges

• Slides selected vertices along exactly one connected visible edge
• Uses panel values: Slide Length and optional Planar (XY) (world XY / plan view)
• Default: exact entered distance along the 3D edge (world-space length)
• Planar (XY): Slide Length applies to world XY–projected displacement (movement still follows the edge in 3D); edges with no XY component in world are skipped
• Ignores hidden edges when checking connectivity
• Non-matching vertices are skipped

---

Slopes and Perpendicular Shared slope inputs

• Percent (%)
• Degrees (deg)
• Ratio (1:x)

These values are synchronized.

Set Slope

• 2 selected vertices
• Applies Z offset on active/last-selected vertex using current slope inputs

Set Slope on Line

• Batch mode
• Supports isolated selected edges or one connected open line

Extrude Vertices ⊥ Planar (mesh XY)

• Extrudes selected vertices along angle bisector (miter) of connected edges
• Builds offset line from selected line/loop with adjustable slope on created edges
• Planar (mesh XY): offset and slope “run” use local XY (edges projected to the mesh XY plane), not world axes unless the object is aligned to the ground
• Angle Correct Length compensates corners to keep offset width more uniform
• Includes Swap Sides

Extrude Vertices ⊥ Fill Planar (mesh XY)

• Same as above, plus side-face fill between neighboring extrusions
• Supports one open non-branching line and one closed non-branching loop

Extrude Vertices ⊥ Fill (Slope Range) Planar (mesh XY)

• Like Extrude Vertices ⊥ Fill, but slope varies linearly from Slope from (%) to Slope to (%) along the line
• Open line only: select one non-branching open line (exactly 2 endpoints); loops are not supported
• Orientation: active endpoint = Slope to; opposite endpoint = Slope from
• Dialog: Slope from (%), Slope to (%), Swap From/To (swap from/to in computation)

Get Slope

• Reads slope from 2 selected vertices
• Writes result directly below the button in UI

Annotate Slopes

• Creates slope text + drop-direction arrows at edge midpoints
• Texts and arrows are always created in a new collection
• Processes all mesh edges (optional length filter in dialog)
• Label format in dialog: Percent (%) or Ratio (1:x)

---

Circles Create Circle Sector 2 selected vertices

• Creates arc between selected endpoints using Radius (World)
• If distance > 2R, radius is remapped internally for computation only
• In remap mode: major arc is used and side is flipped internally for stable behavior
• UI/Redo still shows the user-entered radius value
• Default is 3D (tilted arc plane). Enable Planar (XY) to force plan-view arc generation in world XY
• Tilt can be entered as Percent (%) or Angle (deg) (synchronized); ignored in 3-vertex mode
• Vertex Spacing (World) controls tessellation density

3 selected vertices

• Solves true 3D circle from all selected points
• Generated arc passes through all 3 selected vertices
• Active vertex does not control arc orientation

---

Measure (World Space) Length selected Edges (World)

• Sums world-space lengths of selected edges

Length selected Edges (World) Planar (XY)

• Sums lengths of selected edges projected onto world XY (plan view; edges vertical in world XY contribute 0)

Angle 2 Selected Edges (World)

• Requires exactly 2 selected edges in Edit Mode
• Reports the smaller angle between the two lines in 3D (world space); whether the edges share a vertex does not matter

Angle 2 Selected Edges (World) Planar (XY)

• Requires exactly 2 selected edges in Edit Mode
• Projects both edge directions onto world XY (plan view) and reports the smaller angle
• If an edge has zero planar (world XY) length, the operator reports an error

Area selected Faces (World)

• Triangulates selected faces (nondestructively) and sums world-space area

Area selected Faces (World) Planar (XY)

• Triangulates selected faces (nondestructively) and sums their area projected onto world XY (plan view)

Volume (Selected Solid)

• Computes volume from selected faces
• Selection must be a closed shell

---

Troubleshooting Tool does not run

• Active object must be a Mesh
• Selection count/type must match tool requirements
• Most tools require Edit Mode

Circle sector warnings

• 2-point mode under 2R enters internal remap mode (warning shown)
• Very small spacing with very large effective radius may hit segment safety cap
• 3-point mode requires non-collinear points

Slide does nothing

• Use vertices with exactly one visible connected edge
• Hide edges to exclude them from slide eligibility

Extrude Vertices ⊥ Fill (Slope Range) Planar (mesh XY) fails

• Selection must be one open non-branching line (exactly 2 endpoints)
• Loops and branching selections are not supported

Volume fails

• Selected faces must form a closed shell
• Each boundary edge must belong to exactly 2 selected faces

---

Release Notes

See CHANGELOG.md for version history.