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Update (Mar 2026): This post still documents the original 31-PDF scan-heavy pilot and why the first practical routing rule emerged from that audit. The public OCR benchmark story has moved on since then: the newer workflow-boundary comparison now includes Hunyuan and DeepSeek alongside GLM and FireRed. At that newer workflow boundary, Hunyuan is the strongest grounded workflow, DeepSeek is the second grounded workflow and the strongest blank-page detector, FireRed remains the best balanced workflow, and GLM remains the fastest typical workflow. Use this article for the method and the limits, then use the updated market-map and workflow-fit posts for the current shortlist and deployment answer:
https://instavar.com/blog/ai-production-stack/OCR_SOTA_Feb_2026_Open_Document_AI_Leaderboard https://instavar.com/blog/ai-production-stack/Which_OCR_Model_Fits_Which_Workflow_in_2026
Short version
this page explains how the 31-PDF, 1331-page OCR pilot was run and why the final result changed over time
models tested hands-on in the pilot: GLM-OCR, dots.ocr-1.5, MonkeyOCR, PaddleOCR PP-StructureV3, and FireRed-OCR
This page is for the method, the evidence, and the limits.
Trust basis: this was run self-hosted on a single RTX 3090 Ti 24 GB box, the raw outputs were kept, the harness was versioned as it changed, and every page in the corpus was reviewed at contact-sheet scale before the disputed pages were checked again at higher zoom.
The next section gives the gist in under a minute. The later sections move into the method, evidence, and appendices.
If you only have 1 minute
What we tested:
31 scanned chemistry PDFs
1331 pages
GLM-OCR, dots.ocr-1.5, MonkeyOCR, PaddleOCR PP-StructureV3, and FireRed-OCR
one self-hosted workflow on a single
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this article documents that original scan-heavy pilot, not the newer four-model workflow benchmark
What changed the result:
the early runs made GLM-OCR look like the clear default
that changed only after the FireRed-OCR wrapper was patched to handle near-blank pages and preserve page images
once that happened, the benchmark stopped being a “one winner” story and became a routing story
The routing rule that survived the audit:
FireRed-OCR for text-first pages
GLM-OCR for visual-answer-dependent pages
dots.ocr-1.5 when the requirement is OCR plus broader visual parsing
What the newer workflow benchmark added:
Hunyuan is now the strongest grounded workflow in the measured set
DeepSeek is now the second grounded workflow and the only one to detect all 3/3 blank pages in the current full-50 workflow benchmark
What not to overread:
this is not a universal OCR leaderboard
this is not a semantic-accuracy proof across all document domains
this is a scan-heavy, cleanup-oriented benchmark with a visual audit layer
If you have 5 minutes
The pilot started with a practical question:
On real scanned PDFs, which OCR stack gives the cleanest output for the least downstream cleanup cost, and when should a page be routed to a different model?
That mattered more than asking which model topped a public leaderboard.
What we learned
the most useful result was not a single winner but a page-routing rule
FireRed-OCR became the best default on long notes, tables, bullet-heavy pages, and answer-heavy pages
GLM-OCR stayed safer when the question depends on a local graph, apparatus, reaction scheme, or particle-box option
dots.ocr-1.5 remained interesting, but more as a broader parser than as the default OCR engine for scan-heavy PDFs
Why the benchmark result changed over time
The early 3-way and 4-way runs were exploratory. The final 5-way result changed because the benchmark harness got better, especially for FireRed-OCR.
Two wrapper fixes mattered:
a conservative blank-page gate stopped hallucinations on near-empty scans
page-image preservation stopped figure-heavy pages from being flattened into text-only Markdown
That means the later result is not a mysterious leaderboard reversal. It is a better comparison.
Full decision matrix
Need
Best default from this pilot
Why
Clean Markdown from text-first scanned notes
FireRed-OCR
Lower cleanup burden once blank-page gating and page-image preservation were fixed
Diagram-linked question pages
GLM-OCR
Better inline region preservation for question-local visuals
OCR plus broader visual parsing
dots.ocr-1.5
Better fit when the requirement extends beyond classic document OCR
Mixed PDFs that alternate between notes and figure-heavy worksheet pages
Hybrid routing
Different page types clearly favored different models
Can still lose question-local visuals if a page really depends on them
GLM-OCR
Diagram-dependent question pages
Materially noisier plain-text Markdown on many long note pages
dots.ocr-1.5
OCR plus web, screen, scene, or SVG-style parsing
Not the safest default for scan-heavy school PDFs
PaddleOCR PP-StructureV3
Modular parsing and competitive fallback on messy worksheets
Less clean overall in this Markdown-first comparison
MonkeyOCR
Isolated wins on some pages/documents
Too unstable overall to become the default
What to do with that conclusion
If you are choosing a production OCR workflow, treat this as a routing problem:
one default for text-first pages
one safer model for visual-answer-dependent pages
one optional broader parser if your scope extends beyond document OCR
That is a stronger operational lesson than chasing a single “best” OCR model.
Full methodology
1 What this benchmark was trying to answer
The benchmark question was intentionally narrower than the usual public OCR comparison.
It was not:
“Which model has the highest OmniDocBench score?”
“Which model is best in general?”
“Which model wins on digitally native PDFs?”
It was:
what happens on scan-heavy notes and worksheets,
how often the raw output needs cleanup,
and which failure modes are expensive enough to change the deployment plan.
2 Corpus design
The internal pilot used a narrow but operationally useful slice:
31 PDFs
1331 pages
upper-secondary chemistry notes and worksheets
heavy use of scanned pages, formulas, tables, apparatus diagrams, particle diagrams, answer keys, and mixed question layouts
Three DOCX files in the same source tree were excluded from the OCR bake-off so the comparison stayed PDF-to-PDF and page-for-page.
Why this slice was useful:
it is difficult enough to expose OCR failure modes quickly
it mixes text-heavy pages with diagram-dependent question pages
it is closer to real classroom scan cleanup than to polished benchmark corpora
Why this slice is still limited:
it is only one domain
it over-represents scan-heavy school documents
it should not be treated as a universal proxy for invoices, legal bundles, or clean enterprise PDFs
2.1 A benchmark corpus is not enough without page archetypes
A lot of OCR comparison posts show a few memorable pages without saying which page types are supposed to stress the models. That makes the examples memorable, but it weakens the benchmark.
For future runs, the corpus should always be paired with a smaller archetype suite. The archetype suite is not meant to replace the full corpus. It is meant to make the test explainable.
At minimum, the page archetypes should include:
text-first notes pages
diagram-question pages
table-heavy pages
formula-heavy pages
worksheet answer-option pages
blank or near-blank scans
noisy or skewed scans if those are part of the deployment brief
Different OCR stacks fail in different ways:
some lose local diagrams
some flatten tables
some break formulas
some hallucinate on empty pages
some stay readable on prose but fail once the page becomes option- or figure-dependent
The evaluation should also be reported by slice, not only as one total. That is where slice-level macro-averaging becomes useful.
The cleaner approach is:
score each archetype slice separately
compute a macro-average across slices
still keep the whole-corpus total for operational realism
That prevents a benchmark from looking strong only because it saw many easy text-first pages while quietly failing on diagram-dependent or formula-heavy pages.
2.2 Execution environment
The pilot was run self-hosted on a single NVIDIA GeForce RTX 3090 Ti with 24 GB VRAM.
That was useful for two reasons:
these were not vendor-hosted black-box OCR calls
the serving/runtime constraints were close to what a small production team can actually reproduce on one strong workstation
The practical output target was Markdown-first comparison. Where a model exposed more than plain text, those extra artifacts were retained when useful:
GLM-OCR: Markdown plus region-aware outputs
FireRed-OCR: Markdown plus patched page-image preservation in the final run
PaddleOCR PP-StructureV3: full document parsing output normalized into the comparison flow
dots.ocr-1.5 and MonkeyOCR: raw Markdown-oriented outputs
2.3 Benchmark contract: what has to stay fixed
Models are often shown side by side without keeping the evaluation conditions steady enough for the comparison to mean much.
This pilot did not start with one frozen harness. The final methodology is stricter than the first exploratory runs, and that should be stated directly.
For future runs, the minimum contract should be:
same page set
same page order
same render path for rasterized pages
same target output format for comparison
same hardware disclosure
per-model inference settings documented alongside the output
At a minimum, every run should disclose:
rendering method and resolution
OCR prompt or extraction instruction if one exists
decoding or generation limits if the model is generative
output target (Markdown, HTML, JSON, or normalized proxy)
runtime environment
any post-processing that happens before scoring
Without that contract, the comparison becomes too easy to distort. A model can look stronger or weaker because of truncation limits, low render resolution, missing blank-page handling, or a quiet change in post-processing.
That is exactly why the patched 5-way comparison is more trustworthy than the earlier exploratory passes.
2.4 Benchmark changelog and run versioning
OCR write-ups often present every comparison as though it came from one perfectly frozen harness. That was not true in this pilot, and it should not be hidden.
For each refresh, the workflow should log:
corpus version
archetype-suite version
model versions
inference settings
post-processing steps
scoring logic version
any wrapper fixes that change the outcome materially
That is not bureaucracy. It is the only clean way to explain why a later run changed the ranking.
In this pilot, the practical example was straightforward:
the early 3-way and 4-way runs were exploratory
the later 5-way run changed because the FireRed-OCR wrapper was patched
the ranking shift was therefore a pipeline change, not a mysterious benchmark reversal
3 Model set and run sequence
The exploration did not start with five models at once. It expanded over time as the failure modes became clearer.
3.1 Public benchmark families we track
Before running any internal bake-off, it helps to separate public benchmark families by what they are actually measuring.
The three families worth tracking most closely are:
OmniDocBench for broad document parsing quality across complex page structures
OlmOCR-Bench for narrower OCR-style checks and unit-test-like failure cases
CC-OCR for multilingual and broader cross-category OCR coverage
Those benchmark families are useful, but they should not be flattened into one fake universal leaderboard.
In practice:
OmniDocBench is useful for broad document understanding directionally
OlmOCR-Bench is useful for precise failure-style comparisons
CC-OCR is useful when multilingual or cross-domain OCR behavior matters
What they do not do is replace a fixed in-house bake-off on the page types you actually deploy against.
3.2 Run history
The pilot expanded in three stages.
Raw 3-way comparison
Models:
GLM-OCR
dots.ocr-1.5
MonkeyOCR
Headline result:
wins: GLM=24, dots=2, Monkey=5
Model totals inside that run:
Model
Artifact score total
Notes
GLM-OCR
2117
Clear early default on this corpus
dots.ocr-1.5
5750
Hurt by hallucinations and watermark-like residue in that raw pass
MonkeyOCR
4696
Some strong page/document wins, but unstable overall
What that clarified:
GLM-OCR was the safest early default on this scan-heavy corpus
dots.ocr-1.5 was interesting, but not the safest baseline for pure scanned-document OCR
MonkeyOCR produced some strong document wins, but it was not stable enough to become the default
Raw 4-way comparison
Models:
GLM-OCR
dots.ocr-1.5
MonkeyOCR
PaddleOCR PP-StructureV3
Headline result:
wins: GLM=14, dots=4, Monkey=3, Paddle=10
Model totals inside that run:
Model
Artifact score total
Notes
GLM-OCR
4695
Strongest overall baseline in that 4-way pass
dots.ocr-1.5
6098
Still a weak default for this scan-heavy OCR slice
MonkeyOCR
6755
Too noisy overall despite some wins
PaddleOCR PP-StructureV3
5827
Much more competitive than a paper-only read would suggest
What that clarified:
PaddleOCR was more competitive than a public-paper-only reading would suggest, especially on some messy worksheet-style documents
GLM-OCR still held the strongest overall baseline position
dots.ocr-1.5 remained more compelling as a broader visual parsing candidate than as the default scanned-document OCR engine
Patched 5-way comparison
Models:
GLM-OCR
dots.ocr-1.5
MonkeyOCR
PaddleOCR PP-StructureV3
FireRed-OCR
Before this run, the FireRed-OCR wrapper was patched in two specific ways:
a conservative blank-page gate to stop hallucinations on near-empty pages
page-image preservation so figure-heavy pages were not silently flattened into text-only Markdown
Lowest total in the patched run; 426 page-image refs preserved
GLM-OCR
4655
Strong on diagram-linked pages, but materially noisier on many text-first pages
PaddleOCR PP-StructureV3
5787
Competitive on some messy pages, but less clean overall in this run
dots.ocr-1.5
6053
Better read as a broader visual parser than a pure OCR default
MonkeyOCR
6715
Some document wins, but weakest total in the final run
Important caveat:
the 3-way, 4-way, and patched 5-way runs are all useful
the patched 5-way result should be read as the final routing-oriented comparison because it reflects the fixed FireRed-OCR evaluation path
Another caveat matters for trust: do not read the absolute totals from the early raw runs and the patched 5-way run as one single frozen leaderboard. The harness evolved during the pilot. The useful signals are:
within-run rankings
named failure modes
whether the ranking changed for a defensible pipeline reason
4 Comparison dimensions we score before choosing a model
Public OCR roundups often collapse everything into one question: “which model is best?”
That is not how OCR decisions should be made.
Before promoting any stack, the comparison should at least score or describe these dimensions:
Dimension
Why it matters
What to check in practice
Text fidelity
Raw text still has to be right before anything else matters
A good model that is awkward to serve may still be the wrong choice
Single-GPU fit, batch throughput, wrapper complexity, memory use
Domain fit
Benchmarks underrepresent many real document types
Notes, worksheets, forms, receipts, bank statements, multilingual scans
This is one reason the final routing rule ended up more useful than a single winner. Different models were stronger on different dimensions, and the deployment choice became a routing problem rather than a one-model problem.
5 Scoring and visual audit
The comparison needed something faster than full line-by-line human adjudication across 1331 pages, but more useful than word count alone.
it gives a stable first pass for comparing raw Markdown output at scale
Why it is not enough on its own:
it is not a semantic-accuracy percentage
it does not fully capture lost diagrams
it can over-penalize or under-penalize edge cases if used without manual review
So the benchmark did not stop at the heuristic.
5.2 Manual visual audit layer
The heuristic pass was followed by visual review.
Audit method:
full 31-PDF corpus reviewed at contact-sheet scale across all 1331 pages
deeper zoomed page-level passes on the two remaining GLM-OCR wins
deeper zoomed passes on three ambiguous mixed documents that could not be classified confidently from the contact sheets alone
Every page in the corpus was reviewed visually at contact-sheet scale, and the important disagreements were checked again at higher zoom before any routing conclusion was kept.
The visual audit should publish a compact review packet for the pages that changed the routing policy:
one source-page render
one raw output excerpt from each model being discussed
one sentence on the decisive failure mode
one routing conclusion tied to that page type
6 Failure modes that actually changed the routing
The benchmark became useful only once the failure modes were named clearly.
6.1 Blank-page hallucination
This mattered most for FireRed-OCR early on.
Near-empty scanned pages triggered hallucinated content until the workflow added a conservative blank-page gate. Without that fix, FireRed looked worse than it really was.
Lesson:
evaluation pipelines can distort model quality if they do not treat blank or near-blank scans explicitly
6.2 Inline diagram loss
This is where GLM-OCR stayed valuable.
When a page contains:
a reaction scheme
an apparatus sketch
particle-box answer options
a graph that the question directly references
the OCR problem is not just “read the text.” It is “keep the local visual attached to the question.”
GLM-OCR remained safer on those pages because its inline region preservation was more useful than cleaner plain-text output.
6.3 Text-cleanliness and cleanup cost
Once blank-page handling was fixed, FireRed-OCR often produced cleaner Markdown on:
explanatory notes
answer pages
formula-heavy sections
bullet-heavy revision pages
long text-first classroom notes
Cleanup time is often the hidden cost center in OCR projects.
6.4 Broader parser vs better OCR default
dots.ocr-1.5 stayed interesting, but for a different reason.
It is more valuable when the requirement includes:
That is a genuine product difference. It is not the same decision as picking the safest OCR default for scanned PDFs.
6.5 The early harness and the final harness were not identical
This is worth stating plainly because credibility depends on it.
The raw 3-way and 4-way runs were exploratory passes. The patched 5-way run came later, after the pilot fixed specific evaluation weaknesses, especially around FireRed-OCR.
That means:
the early runs were still useful
the final run is the most trustworthy routing-oriented comparison
the real story is not “one model flipped the leaderboard overnight”
The real story is that the benchmark got better once the pipeline handled blank pages and figure preservation more honestly.
7 Concrete documents that changed the routing policy
The benchmark would have been much less useful if it only ended with aggregate win counts.
These documents are the ones that actually changed the policy.
7.1 GLM-only case
Topic 1B Identification of Ions and Gases stayed a GLM-OCR document.
Why:
almost every page depended on small inline reaction schemes or figure-linked question content
page-level image links were not enough because the diagram had to stay tied to a specific question
This was the clearest case where cleaner text alone was not the right success metric.
7.2 Hybrid cases
These documents were mixed enough that whole-document routing lost quality:
Elements, Compounds and mixtures notes
Kinetic Particle Notes
Elements, Compounds and Mixtures Worksheet
Speed of Reaction Worksheet
The shared pattern was consistent:
question pages with graph, apparatus, or particle-box answer options leaned GLM-OCR
worked answers, explanation pages, and text-heavy notes leaned FireRed-OCR
7.3 FireRed-heavy wins
The documents that made the FireRed-OCR case sharper were the text-heavy note packs and answer-heavy pages, including examples such as:
Acids and Bases Notes
Ionic Bonding Notes
Energy Changes
Electrolysis
The Atmosphere and Environment
Those files made it clear that once blank-page hallucinations were controlled, FireRed often reduced the cleanup burden on long note pages materially.
8 The routing rule that survived the audit
The most useful result from the benchmark was a routing rule that generalizes better than “best model.”
Use:
FireRed-OCR for text-first pages
GLM-OCR for visual-answer-dependent pages
dots.ocr-1.5 when the real requirement extends beyond document OCR into broader visual parsing
In practice, the page types that leaned GLM-OCR were:
“the diagram below” questions
apparatus questions
graph-selection questions
particle-box answer choices
local reaction schemes
MCQ pages where the options themselves are images
The page types that leaned FireRed-OCR were:
explanatory notes
bullet lists
worked answers
answer keys
tables
formula-heavy pages
long prose-heavy revision notes
The mixed-document outcome matters too:
some PDFs should not be routed whole-doc to one model
a single file can alternate between text-heavy notes and figure-dependent worksheet pages
What this benchmark does not prove
This benchmark does not prove that FireRed-OCR is the best OCR model in general.
It also does not prove that GLM-OCR is weak, or that dots.ocr-1.5 is a poor release.
It proves something narrower and more operationally useful:
on one hard scan-heavy corpus
with this scoring method
and with manual visual audit layered on top
the routing rule mattered more than the public leaderboard story
That is a better deployment lesson than chasing one winner.
Appendix A: Concrete page evidence from the pilot
Aggregate totals were useful, but the routing rule only became credible once the decisive page types were visible.
The examples below are taken from the actual scan-heavy pilot. They are not polished post-processed outputs. The point is to show what the models did before editorial cleanup.
Example 1: FireRed on a text-first notes page
This page is mostly linear text with a simple formula mention. That is where FireRed-OCR tended to reduce cleanup burden.
FireRed excerpt:
(b) describe the formation of ionic bonds between metals and non-metals, e.g. NaCl; MgCl₂
GLM excerpt:
(b) describe the formation of ionic bonds between metals and non-metals, e.g. NaCl; $ \mathrm{M g C l\_{2}} $
That is a small example, but it matters. On long note pages, repeated chemistry-token damage adds up quickly.
Example 2: GLM on an inline reaction-scheme question
This is the page type where GLM-OCR stayed safer. The question is not only about text. It depends on the local reaction scheme.
GLM excerpt:
1. The diagram shows a reaction scheme for compound X.
What is compound X? (N2008/P1/Q2)
FireRed excerpt:
1. The diagram shows a reaction scheme for compound X.
What is compound X?
A aluminium sulphate
B calcium carbonate
C copper(II) carbonate
D zinc carbonate
The FireRed text is readable, but the question-local diagram is no longer preserved inline. So this document stayed GLM-OCR.
Example 3: Why mixed documents need hybrid routing, part 1
This page comes from one of the documents that ended up in the hybrid bucket rather than the GLM-only bucket.
On text-and-table pages like this one, FireRed was already good enough to be the better operational choice:
### 1. Elements
☐ An element is a pure substance that cannot be broken down into simpler substances by any chemical methods.
## Chemical Symbols of Elements
<table><tr><td>Element</td><td>Symbol</td></tr><tr><td>Hydrogen</td><td>H</td></tr><tr><td>Oxygen</td><td>O</td></tr>...
That is also why the document did not stay on GLM-OCR wholesale. Some pages were already cleaner and easier to work with in FireRed.
Example 4: Why mixed documents need hybrid routing, part 2
The same document later switches into a diagram-linked worksheet page. This is where GLM-OCR was safer.
GLM excerpt:
3. The diagram shows hydrogen gas being burnt.
( a ) Name two elements that are involved in the reaction. [2]
...
4. Chemical substances may consist of three types of particles - atoms, ions or molecules.
...
FireRed excerpt:
3. The diagram shows hydrogen gas being burnt.
(a) Name two elements that are involved in the reaction. [2]
(b) (i) Name the colourless liquid. [1]
...
4. Chemical substances may consist of three types of particles - atoms, ions or molecules.
(a) What do you understand by the following terms?
(i) atom
(ii) ion
This is the same PDF as Example 3. One page type leans FireRed-OCR; the other leans GLM-OCR. Hybrid routing was not an edge case here. It was a real deployment requirement.
Example 5: Why benchmark versioning matters
This page is the clearest example of why run versioning belongs in the methodology itself.
Earlier FireRed run:
<!-- page 58 -->
The 7 Habits of Highly Effective People
The model did not become magically different overnight. The wrapper changed. That is exactly why benchmark changelogs and run-versioning have to be explicit.
Appendix B: Full workflow to reuse the method
If an OCR team wants a practical first benchmark instead of a benchmark-shaped press release, a sensible process is:
Build a corpus that mixes:
text-first pages
diagram-dependent pages
tables
formulas
answer keys
blank or near-blank scans
Define a smaller archetype suite so the benchmark has named page types, not only a blob of documents.
Lock the benchmark contract:
same pages
same render path
same output target
per-model settings disclosed
Run the same pages through every candidate stack.
Score cleanup-oriented artifacts, not just word count.
Publish raw page outputs for the pages that actually changed the decision.
Add visual review before promoting any model.
Treat routing as part of the product, not as a post-hoc patch.
