Repeatable post-processing
A versioned rnx2rtkp configuration file, the RBMC base downloaded by day and station, and a per-point summary of fixed and float epochs.
.pos + summary to accept or redo
Octo for surveying with free software
From RINEX to the legal description, license-free. The signature is still yours.
RTKLIB, IBGE-PPP, PROJ, QGIS with GeoINCRA and LF Tools, PDAL, GDAL and OpenDroneMap cover the chain from the field to delivery, in scripts that run on Linux. Octo chains the steps together, runs them on a copy and shows the result for checking. What free software lacks (support with a guaranteed response time, integrated adjustment of mixed networks, some proprietary formats) is stated here plainly, and the ART (or TRT, for a technician), acceptance of points and submission to SIGEF stay with the licensed professional.
RTKLIB-EX2.5.1Jun 22, 2026, BSD license
QGIS4.2.3LTR 3.44.15, both from Sep 25, 2026
Paid licenses0across the whole chain on this page
Sources16listed at the end of the page
01
What Octo does with the open chain.
Six possible deliverables, drawn from the research. All of them run on a copy of the field data, which stays untouched, and all of them go to the person technically accountable for the work to check.
Reading IBGE-PPP
A person submits the RINEX through the form; Octo reads the summary text, compares it with the coordinate used and, if needed, applies the base correction to the RTK points.
Deliverable: provisional base vs PPP comparisonSIGEF spreadsheet by script
Checks the GeoRural layers and generates the ODS spreadsheet with GeoINCRA, without opening QGIS, with the area in SGL calculated two ways.
Deliverable: spreadsheet for the accredited professional to check and submitLegal description and plan
Legal description through LF Tools or a custom script with PROJ, and a DXF plan with ezdxf, with azimuths, distances and adjoining owners taken from the same table.
Deliverable: draft legal description + DXFDrone to DTM
ODM in a container, ground reclassified with SMRF in PDAL, DTM and contours with GDAL, and differences against check points in CloudCompare.
Deliverable: DTM, contours and residuals reportIndependent check
The same data processed in commercial and free software, with the differences tabulated. It validates each against the other and helps decide where each one belongs.
Deliverable: per-point table of differences
02
Eight arms, one open chain.
The same Octo cycle, applied to free surveying software. Each arm has a narrow role; the ones who accept points, sign and submit to the public agency are people.
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Discovery
Surveys what already exists
Field files, receivers and formats, installed versions, QGIS plugins and what the team does today in commercial software.
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Data
Pins down references
SIRGAS 2000, epoch, UTM zone, height type, vertex codes and the data model (GeoRural, TopoGeo).
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Security
Looks after access and data
Raw field data untouched, no SIGEF or gov.br credentials in scripts, personal data of owners and adjoining owners handled with the client (LGPD, Brazil's data protection law).
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Architecture
Chooses the path
RTKLIB or IBGE-PPP,
qgis_processor PyQGIS, ODM or a commercial package, and where the commercial tool should stay. -
Development
Writes the scripts
Bash, Python and configuration files, with logging, checks before writing and the source of each syntax noted in the file.
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Review
Checks against a known case
An already certified property, an old survey or the same data in commercial software: checks by the numbers, point by point.
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Release
Delivers to the project folder
Spreadsheet, legal description, plan and DTM go to the agreed folder. Submission to SIGEF and to the client is done by a person.
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Documentation
Records what applies to your project
The version of each tool, configuration file, parameters and result of each processing run, so it can be redone the same way a year from now.
Octo works in a support role. It does not accept points on its own, does not sign legal descriptions, does not file an ART (or TRT, for a technician) and does not submit anything to SIGEF: that belongs to the licensed professional.
03
Each step: the free option and what's missing.
The honest comparison with commercial software. Free software wins on repeatability and license cost; it loses where the table says so.
| Step | Free path | Compared with commercial |
|---|---|---|
| Raw receiver data to RINEX | convbin (RTKLIB-EX) | Covers several brands; some require the vendor's converter |
| Relative post-processing | rnx2rtkp -k arquivo.conf | Strong and scriptable; no guided interface |
| Official PPP | IBGE-PPP (form) and reading the summary text | Same for everyone; accepted by INCRA according to IBGE |
| SAD69 or Córrego Alegre to SIRGAS 2000 | cs2cs with PROJ's br_ibge_* grids | Same grid as IBGE |
| Normal height (hgeoHNOR2020) | IBGE program or IBGE-PPP report | Grid not found on the PROJ CDN |
| GNSS + total station network adjustment | Closed traverse in LF Tools; early-stage network plugins | The main gap in free software |
| SIGEF ODS spreadsheet | GeoINCRA (GeoRural to ODS Spreadsheet) | Covers the workflow; community support |
| Legal description | lftools:descriptivememorial or a script with PROJ | Covered; the final text always belongs to the person accountable |
| Drone photogrammetry | OpenDroneMap in a container | Works; speed and finish not compared by measurement |
| Ground and DTM | PDAL (filters.smrf, writers.gdal) and GRASS | Very capable by script |
| Plan | ezdxf (script) and LibreCAD (review) | DXF yes; DWG and design features are the limit |
| Support | Community, issues, courses and consultancies | No contract with guaranteed response times: a real difference |
04
From a side-by-side test to a mixed office.
Three steps. Each one only makes sense after the previous one has shown results in your surveying office.
A proposal, not a promise
Independent check
A job already delivered is redone with the free chain, and the differences are tabulated point by point.
- Same RINEX in RTKLIB and in the current package
- Area in SGL calculated two ways
- Inventory of what free software can't read
Repetitive batches on free software
What repeats (daily post-processing, spreadsheets, legal descriptions, contours) moves to scripts with versioned configuration.
- RBMC base downloaded by the script
- SIGEF spreadsheet and legal description from the GeoPackage
- Drone DTM with tabulated residuals
Mixed office
Commercial software stays where it is irreplaceable (integrated adjustment, proprietary formats); free software runs on a Linux server for everything else.
- Overnight processing queue
- Version and parameter log for each job
- Commercial licenses only where they make a difference
05
Confirmed by a source.
Every point below has a source published by the responsible agency (Planalto, INCRA, IBGE, ANAC, DECEA), by the vendor or by the project. ABNT standards appear only by number and title. The sources are in the next section.
4
points with a published source, each with its reference shown alongside.
- ConfirmedIBGE-PPP: accepted by INCRA, according to IBGE
- A free service built on NRCan's CSRS-PPP; coordinates in SIRGAS 2000 at epoch 2000.4; summary text for automated reading since 2022; orbits in IGc20/ITRF2020-u2024 since Jan 11, 2026. The page says the results "are accepted by INCRA" and cites as its basis the 2013 technical manual, which predates INCRA's current manual (2nd edition, 2022). No page promises certification.Source: IBGE-PPP page (ibge.gov.br)
- ConfirmedThe maintained RTKLIB is RTKLIB-EX
- The last release of the original RTKLIB is 2.4.3 b34, published on GitHub on Jan 6, 2021. RTKLIB-EX, "formerly RTKLIB demo5", released 2.5.1 on Jun 22, 2026, builds with CMake on Linux and is 2-clause BSD.Source: releases and project pages on GitHub
- ConfirmedBrazilian plugins with processing support
- GeoINCRA 2.0.4 (MIT) generates the SIGEF ODS spreadsheet and calculates area in SGL; LF Tools 2.18.2 (GPL v3) has legal descriptions, closed traverse, SGL and import of RTKLIB
.posfiles. Both include a processing provider.Source: plugins.xml from the QGIS repository and code on GitHub - ConfirmedIBGE grids in PROJ
- The PROJ CDN has IBGE grids from SAD69, SAD69(96), Córrego Alegre 1961 and 1970-72 to SIRGAS 2000. It has no hgeoHNOR2020 grid.Source: cdn.proj.org/files.geojson
06
What Octo does, and what stays with you.
Octo prepares everything, but it does not sign. The document of record stays with whoever is accountable for it.
Octo prepares
Surveys, calculates, organizes and produces the documents: spreadsheets, reports, drawings and draft legal descriptions.
Deliverable: material ready to checkYour team checks
The licensed professional checks what Octo delivered before signing. If something doesn't add up, it goes back to Octo with the correction.
Step: checked by the person who signsWho signs
Octo does not sign. Designs, technical reports, ART/RRT, statements of account and any official document are still signed by the licensed professional at the company or agency: here, the surveying or cartographic engineer with an ART filed with CREA, or the surveying technician with a TRT filed with CRT; for rural properties, the professional accredited by INCRA, who submits to SIGEF.
Signature: licensed professional, with ART or TRT
07
Sources.
Official pages, repositories and project documentation, consulted on Oct 31, 2026.
- RTKLIB-EX, releases2.5.1 and release notes
- RTKLIB manual (demo5 project)convbin, rnx2rtkp and options
- IBGE-PPPInput, output, reference frame and acceptance
- RBMC, data repositoryDaily files by station
- PROJ, grids on the CDNbr_ibge_* grids
- PROJ, topocentricLocal plane
- QGIS, command-line processingqgis_process
- GeoINCRASIGEF ODS spreadsheet and SGL
- LF ToolsLegal description, traverse, .pos
- OpenDroneMap, arguments--dsm, --dtm, --gcp
- PDAL, filters.smrfGround classification
- GDAL, gdal_contourContour lines
- CloudCompare, command-line commandsC2C_DIST, ICP, SS
- ezdxfDXF by script
- Law 10.267/2001Legal description with ART, georeferenced to the SGB
- INCRA Ordinance No. 2.502/2022MTGIR 2nd edition
Your next survey, checked two ways.
The assessment starts with a job your office has already delivered, redone with the free chain without touching the original. You get the differences point by point and a proposal for what can move to scripts, and you decide with that in hand.