Feature Codes, DXF, and LandXML: A Field-to-Finish Workflow

A coordinate is not yet a deliverable. The office still needs to know what was measured, how it should be drawn, which attributes belong to it, and which coordinate frame the numbers use. A field-to-finish workflow carries those decisions from the shot into CAD or survey software instead of asking someone to reconstruct them from notes.

The feature code is the join between field and office

A good feature record has several distinct pieces:

• Name or point number identifies this individual observation, such as MH-104.
• Feature code describes what it is, such as MH for manhole.
• Geometry says whether it is a point, an open line, or a closed area.
• Layer tells CAD where to place it, for example V-SSWR-MHOL.
• Attributes carry the structured facts an office will filter, label, or symbolize: material, diameter, condition, owner, or inspection date.

Collapsing these into a single description field feels quick in the field and creates cleanup later. Structured attributes let a choice arrive as a choice and a number arrive as a number. The office can filter every concrete manhole over 1,000 mm without first standardizing five spellings and removing units from text.

A code library should be editable where the discovery happens

Many systems assume the office has already designed a perfect schema and pushed it to the crew. Fieldwork is where the missing field is usually discovered. If a crew learns that pipe material matters halfway through a job, the practical response is to add it immediately, not wait for a desktop administrator.

OpenSurvey3D lets each feature type define its code, CAD layer, and attribute fields on the device. Fields can be text, number, choice, date, or yes/no; numeric fields can carry a unit; important fields can be marked required. A missing required value produces a warning, but it does not block the crew from recording an honestly incomplete observation.

Schema changes also should not erase field data. If an attribute is removed from the current form, values already collected under it remain on their assets and in exports. Preserving an old value is safer than silently rewriting the historical record to match today's form.

DXF carries the drawing

DXF is the broadest open bridge into CAD. A useful survey export needs more than a cloud of anonymous points. OpenSurvey3D writes R12 DXF because it is widely readable and the geometry here does not require newer entities:

• Point features become POINT entities with visible text labels.
• Lines and areas become polylines, with closed areas explicitly marked.
• Each entity lands on the layer defined by its feature type.
• Feature code, name, description, role, and attributes travel as registered XDATA.
• The file declares insertion units and states the coordinate frame in its header comments.

That layer mapping is what lets an existing office standard take over. If MH maps to V-SSWR-MHOL, the drawing can inherit the office's color, symbol, linetype, and visibility rules the moment it opens.

LandXML carries survey meaning

DXF carries a drawing; LandXML carries survey points and plan geometry. In a LandXML 1.2 export, point names and codes remain explicit, lines and rings travel as plan features, and the coordinate-system and unit declarations sit inside the file rather than in an email beside it.

OpenSurvey3D writes point coordinates in LandXML's required northing, easting, elevation order. It also includes feature notes and typed attributes in the description available to receiving software. The result is suitable for survey packages that want named, coded points rather than graphics to trace.

CSV and GeoJSON are still essential

CAD and survey packages are not the only destinations. CSV is ideal for inspection, spreadsheets, databases, and custom processing; GeoJSON preserves true point, line, and polygon geometry for GIS. Both retain the feature code and attribute values. When a projected coordinate system is selected, exports include the frame needed to interpret easting, northing, and units.

A complete project bundle then packages the open data with its supporting record: checks, photos, scans, and site-model files. The individual formats remain useful on their own; the bundle prevents the context from becoming separated during handoff.

Field habits that keep the pipeline clean

1. Agree on short, stable feature codes before the job, but let the library evolve when reality demands it.
2. Use pick lists for values the office will symbolize or filter.
3. Keep units in the schema, not typed repeatedly into the value.
4. Set the project coordinate system before importing projected design coordinates or exporting CAD.
5. Open a test DXF and LandXML in the receiving software before collecting the entire job.
6. Deliver the QA report and coordinate-frame statement with the geometry.