Octo for systematic mapping

The sheets come out in batch. The one who signs the map is you.

From the 1:1,000,000 map down to 1:25,000, each sheet is a fixed subdivision of the one above it. That is why a script can compute the index code, the UTM zone and the bounds of any sheet, cross-check them against the Digital Index Map collection and generate dozens of sheets with the QGIS atlas without opening the interface. Map design, PEC class, ART and approval stay with licensed people and with the agencies of Brazil's National Cartographic System (SCN).

Request an assessment See what it does

Standard scales6from 1:1,000,000 to 1:25,000 (DL 243/1967)

1:100,000 sheets3036MI from 1 to 3036 (IBGE, 1999)

BC2502025seventh version, ET-EDGV 3.0

Sources15listed at the end of the page

What Octo does in systematic mapping.

Six possible deliverables, drawn from the research. All of them work by reading the official datasets, and all of them go to review by whoever is accountable for the map.

Sheet indexing

Computes every sheet at a given scale that covers a municipality, a watershed or a parcel, with the index code, bounds, UTM zone and the percentage of each sheet inside the area.

Deliverable: sheet layer + review spreadsheet

INOM and MI checked

Finds mistyped index codes in collection spreadsheets, computes the bounds from the code and looks up the MI in the Digital Index Map table, because the MI can't be derived from a formula.

Deliverable: list of discrepancies per sheet

Batch sheets with the atlas

Runs the approved map layout through qgis_process, one PDF per sheet, filtered by batch and review status, with a dry run before and a count after.

Deliverable: batch of PDFs + log + hashes

Sheet index diagram

Computes the eight neighboring sheets of each map for the margin, as article 18 of Decree 89.817/1984 requires, and checks that the printed diagram matches the sheet.

Deliverable: neighbors per sheet, ready for the layout

Coverage inventory

Cross-checks the 4th edition of the Digital Index Map collection with the municipal boundaries: best available scale, age of the latest sheet and legacy datum, by municipality.

Deliverable: table and map of outdated coverage

Correct zone and projection

Flags areas that cross UTM zones, gives the SIRGAS 2000 EPSG code for each sheet and sets aside older sheets in SAD 69 or Córrego Alegre for separate handling.

Deliverable: sheet by sheet, zone, EPSG and datum

Eight arms, one batch of sheets.

The same Octo cycle, applied to systematic mapping. Each arm has a narrow role; the people who design the map, approve the sheets, classify them under the PEC and sign are people.

Discovery
Surveys what already exists

Scales in use, the current layout, the sheet collection, the software (QGIS, ArcGIS or other) and the client's own sheet system for scales larger than 1:25,000.
Data
Pins down references

The area's CRS, each sheet's zone, the Digital Index Map table, municipal boundaries and the version of each dataset, with dates.
Security
Takes care of access and data

Respects each sheet's confidentiality category, uses read-only access to the official datasets and no database password in the script. Confidential data doesn't go to an outside service without agreeing on handling with the client.
Architecture
Picks the path

QGIS atlas, PyQGIS or ArcPy; GPKG or PostGIS; one projection per sheet, or a single mosaic when the area crosses zones.
Development
Writes the scripts

Indexing, batch and inventory, with simulation, dry run, log and the source of each rule (decree, IBGE manual) noted in the file.
Review
Checks on a known case

SD-23-Y-C-IV ↔ MI 2215, the example from the IBGE manual, and a sample sheet from the client. Checks by the content of the PDF, not by the absence of errors.
Release
Delivers for review

Only with your OK, it delivers the batch and the report. It doesn't publish, approve or send anything to the client agency.
Documentation
Records what applies to your project

Scale, zone, QGIS version, layout, sheet list and hashes for each delivery. A batch from one contract is not assumed ready for another.

Octo works with read access and as support. It does not sign maps, classify under the PEC or approve products: that belongs to a licensed cartographic engineer, with an ART, and to the SCN agencies.

Each task, its own path.

The criteria Octo uses to choose. Always with the documentation for the version installed at the client.

Task	Path	Note
Find the sheet for a point	`inom.folha_do_ponto(lat, lon, escala)`	Calculations in arc seconds
Bounds from the INOM	`inom.folha_do_inom("SD-23-Y-C-IV")`	Check against the manual's example
Sheets covering an area	`articulacao_folhas.py`	Discards what only touches the bounding box
MI of a sheet	DIM 4th ed. table (`indNomenclatura`, `mi`)	Not derived from a formula
Neighboring sheets for the margin	`inom.vizinhas(folha)`	Art. 18 of Decree 89.817/1984
Generate sheets in batch	`qgis_process run native:atlaslayouttomultiplepdf`	Layout approved by a person
A single sheet	`native:printlayouttopdf` or PyQGIS	Same check
Coverage by municipality	PostGIS (`cobertura_mapeamento.sql`)	Area as `geography`
Download vector sheets	IBGE geoftp, folder for the scale	Check each sheet's datum
Scale larger than 1:25,000	The client's own sheet system	No confirmed national standard

From the sheet spreadsheet to the monitored batch.

Three steps. Each one only makes sense after the previous one has shown results with your mapping team.

A proposal, not a promise

1 Today

Indexing and checking

You give the area and the scale; Octo returns the sheets, the INOM, the MI and what exists in the collection, with the manual's example as a test.

Sheet layer with a review spreadsheet
INOM check in old spreadsheets
Warnings for zones and legacy datums

Benefit: the sheet list is right the first time

2 Next

Sheets in batch

The approved layout runs through the atlas without the interface, with a dry run, a status filter and checks by count and hash.

One PDF per released sheet
Computed sheet index diagram
Log of each batch

Benefit: the team reviews sheets instead of redoing layouts

3 Later

Inventory and planning

The collection becomes a table you can query by municipality, with age, scale and datum, to support the agency's update plan.

Coverage and outdated areas by municipality
Map of gaps
Priority criteria set by the agency

Benefit: the plan starts from numbers, not memory

Confirmed by sources.

Every point below has a source published by the responsible body (Planalto, IBGE, the Brazilian Army, CONCAR), by the project or by the standards organization. The sources are in the next section.

points with a published source, each with its reference alongside.

ConfirmedScales and who standardizes them: The standard scales are 1:1,000,000, 1:500,000, 1:250,000, 1:100,000, 1:50,000 and 1:25,000; series at 1:250,000 and larger fall to the DSG (the Army's Geographic Service Directorate) and smaller ones to IBGE.Source: Decree-Law 243/1967, art. 8 and art. 15
ConfirmedINOM and MI: The index code starts from the 1:1,000,000 sheet and goes down to 1:25,000; SD-23-Y-C-IV corresponds to MI 2215, and the 1:50,000 and 1:25,000 sheets get 1 to 4 and NO, NE, SO or SE.Source: IBGE, Noções Básicas de Cartografia (1999), sections 2.5 and 2.6
ConfirmedSheet collection in the DIM: The 5th edition of the Digital Index Map (2021) left out the topographic sheets from the DSG and other agencies; they remain in the 4th edition (2011), which has the fields indNomenclatura, mi, anoEdicao and datumHorizontal.Source: technical note 01/2021 and the 4th edition readme (IBGE)
ConfirmedCONCAR became Congeo: Decree 12.402/2025 amended the INDE decree: the functions previously assigned to CONCAR pass to Congeo, to be established by act of the Minister of Planning and Budget (art. 6), with support from IBGE.Source: Decree 6.666/2008 as amended (planalto.gov.br)
ConfirmedAtlas from the command line: native:atlaslayouttomultiplepdf accepts a coverage layer, filter, sort order, folder and file name by expression, DPI and georeferencing; qgis_process runs without a display with QT_QPA_PLATFORM=offscreen.Source: QGIS 3.44 documentation

What Octo does and what stays with you.

Octo prepares everything, but 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, sheets, maps and drafts.

Deliverable: material ready to check

Your 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: review by the signer

Who signs

Octo does not sign. Designs, technical reports, ART/RRT (Brazil's professional responsibility records), accountability reports and any official document are still signed by the company's or agency's licensed professional: here, the cartographic engineer or another licensed professional, with an ART; official data goes into the INDE only after approval by the competent authority.

Sign-off: licensed professional, with ART

Sources.

Legislation, IBGE and DSG documentation and software documentation used in the research, accessed on October 31, 2026.

Decree-Law 243/1967Standard scales and who standardizes them
Decree 89.817/1984Sheet indexing, PEC, diagram, references
Decree 6.666/2008 (INDE)With the 2025 amendments (Congeo)
Decree 12.402/2025Original text (Chamber of Deputies): CONCAR passes to Congeo
IBGE, Noções Básicas de CartografiaINOM, MI and map classification
Digital Index Map, 4th editionFields of the sheet collection
Digital Index Map, technical note 01/2021What changed in the 5th edition
IBGE, topographic sheetsVector, edited and photolithographic
BC250, 2025 versionGeneral technical documentation
DSG ToolsDSG plugin for QGIS
QGIS, qgis_processProcessing from the command line
QGIS, cartography algorithmsAtlas and layout to PDF
QGIS, release roadmap4.2.3 and LTR 3.44.15
GDALStable version 3.13.3
Law 6.496/1977Technical Responsibility Record (ART)

Your sheet indexing, right the first time.

The assessment starts with an area and a scale your team already works with, without touching any official dataset. You get the sheet list, what exists in the collection and a proposal for what can be generated in batch, and decide with it in hand.

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