Spatial Stack with Matt Forrest

In this episode of the Spatial Stack, Matt sits down with Jake Low, software developer at OpenStreetMap US and maintainer of MapRoulette, OSMCha, Field Papers, and Layercake.
Jake explains how a map that anyone can edit takes in about 40,000 changesets a day, and why his job is building tools for the community rather than gatekeeping it. He walks through every way people contribute, from StreetComplete on your phone to JOSM on the desktop to Field Papers, a pen-and-paper workflow used in disaster response and elementary school classrooms.
The conversation also covers getting data back out of OpenStreetMap, from Layercake's thematic GeoParquet extracts to Sourdough, a new vector tile schema inspired by CSS Zen Garden. Jake breaks down the ODbL license in plain English, how companies like Amazon are paying contractors to map rural driveways, and why 80% of maintaining open source infrastructure is just keeping it alive.
Whether you're making your first edit tonight or pulling the planet file into DuckDB, this conversation shows you how the world's open map actually runs.
Connect with Jake:
Website: https://www.jakelow.com/
GitHub: https://github.com/jake-low
OSM US Slack: https://slack.openstreetmap.us
OpenStreetMap US: https://openstreetmap.us
SUPPORT
Support OSM US: https://openstreetmap.us/get-involved/donate/
LEARN MORE
Field Papers: https://openstreetmap.us/our-work/field-papers/
Layercake: https://openstreetmap.us/our-work/layercake/
OSMCha: https://openstreetmap.us/our-work/osmcha/
MapRoulette: https://openstreetmap.us/our-work/maproulette/
CHAPTERS:
00:00:00 – Intro
00:02:03 – Welcome and Jake's background
00:03:44 – 40,000 changesets a day and OSMCha
00:07:28 – What OpenStreetMap US does
00:11:19 – Contributing at every scale: StreetComplete to JOSM
00:13:11 – Mapping with pen and paper: Field Papers
00:15:56 – Start tonight: MapRoulette and 10,000 duplicate reservoirs
00:19:32 – Gamification, paid mapping, and Amazon driveways
00:22:49 – Sourdough and the CSS Zen Garden idea
00:28:11 – Layercake: OpenStreetMap as GeoParquet
00:31:58 – The ODbL license in plain English
00:34:53 – Keeping open source infrastructure alive
00:41:21 – What people get wrong about OpenStreetMap
00:43:45 – Rapid fire: DuckDB, WebGPU, and Yesterdays
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In this episode of the Spatial Stack, Matt sits down with Dr. Chris Tucker, chairman of the American Geographical Society, in the year the AGS turns 175.
Chris makes the case that spatial thinking is foundational literacy, on the level of language or math, and that the 4.5 million people who have taken AP Human Geography are already practicing it every day in jobs that never mention geography. He shares how a single question from a CIA veteran, about why we cannot draw a bounding box on a map and pull in everything known about that place at that moment, set the direction for almost thirty years of his career.
The conversation also covers what has changed about getting into this work. The advanced degree, the expensive workstation, and the expensive software used to be the price of entry. Free tools and YouTube replaced all three.
Chris then takes on a challenge: name five careers that do not sound geographic but where spatial skills give you a real edge. Surveying, the CAD and built environment world, aviation, marine navigation, and conservation all make the list, along with a case for why geography works as both a horizontal and a vertical.
We also get into the AGS itself, from the Fliers' and Explorers' Globe signed by Amelia Earhart, Sir Edmund Hillary, and Neil Armstrong, to the geographers at 156th and Broadway who worked on the inquiry behind the Treaty of Versailles.
If you have ever struggled to explain what you actually do for a living, this conversation gives you better language for it.
Connect with Chris Tucker and the AGS:
LinkedIn: https://www.linkedin.com/in/christopher-tucker-5595689/
American Geographical Society: https://www.americangeo.org
Email: tucker@americangeo.org
LEARN MORE
AGS 175th anniversary campaign: https://www.americangeo.org
The Fliers' and Explorers' Globe: https://www.americangeo.org/globe
Geography 2050 (Africa: Shaping the Future): https://www.geography2050.org
Teen Maptivist: https://teenmaptivists.org
CHAPTERS:
00:00:00 – Welcome and Chris Tucker's Background
00:01:21 – 4.5 Million AP Human Geography Students
00:04:48 – Spatial Thinking as Foundational Literacy
00:09:08 – 175 Years of the American Geographical Society
00:12:03 – The Fliers' and Explorers' Globe
00:15:05 – The AGS and the Treaty of Versailles
00:18:02 – The 175th Anniversary Campaign
00:21:49 – How Matt and Chris Found Geography
00:24:59 – Free Tools and Getting Back Into the Work
00:27:07 – Advocating for Geography in Schools
00:30:55 – Geography as Horizontal and Vertical
00:35:01 – Five Careers Where Spatial Gives You an Edge
00:40:34 – Getting Involved with AGS and Geography 2050
---
📊 FREE: The Modern GIS Skill Map
The 5 skills that actually matter in modern GIS (and what you can stop learning). Based on a survey of 1,400+ geospatial professionals.
➡ Get the free training + PDF guide: https://forrest.nyc/go/training/
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What does it take to map something you have never seen?
In this episode, Matt Forrest sits down with Justin Stewart, quantitative ecologist at SPUN, the Society for the Protection of Underground Networks, to unpack how his team built the first global map of arbuscular mycorrhizal fungi, the soil organisms living in symbiosis with most plants on Earth.
Justin walks through the full pipeline, from robotic microscopy of threads two and a half microns wide up to a planetary prediction at one square kilometer resolution. The team assembled 16,000 soil samples from more than 300 studies across 11 languages, trained a random forest on 34 satellite-derived layers in Google Earth Engine, and
summed the result: roughly 110 quadrillion kilometers of fungal thread, about 300 megatons of carbon, six times the biomass of every human alive.
The findings were not what anyone expected. The densest networks are under grasslands, not forests. Croplands run about 50 percent sparser. And 90 percent of the biodiversity hotspots for these fungi sit outside any protected area.
In this episode, we cover:
- Why mapping a symbiosis is harder than mapping an organism
- Robotic imaging in the Amolf biophysics lab, and tracking half a million nodes at once
- Building a global database from literature in 11 languages
- Random forest niche modeling and uncertainty analysis in Google Earth Engine
- The effective radius algorithm that turns network length into biomass
- Why grasslands, flooded wetlands, and the Tibetan plateau light up on the map
- Tilling, fertilizer, and how a 450 million year old symbiosis gets broken
- Rights of nature, eDNA, and why predictive maps are not yet admissible evidence
LINKS:
Justin Stewart
SPUN profile: https://www.spun.earth/team-members/justin-stewart
LinkedIn: https://www.linkedin.com/in/justin-stewart-70512645/
Google Scholar: https://scholar.google.com/citations?hl=en&user=1aqTJIUAAAAJ
SPUN
Website: https://www.spun.earth
Underground Atlas: https://a-hidden-infrastructure.spun.earth/story/a-hidden-infrastructure
LEARN MORE
The paper: Science, June 11, 2026. DOI 10.1126/science.adu4373
Mycorrhizal Biodiversity Map: https://a-hidden-infrastructure.spun.earth/story/a-hidden-infrastructure
CHAPTERS:
00:00:00 – The largest living network on Earth
00:02:15 – Welcome and intro
00:03:38 – What the map shows: a partnership, not an organism
00:05:48 – Robots, petri dishes, and carbon moving at 400 kilometers an hour
00:07:47 – The question that started it: how much is out there?
00:09:25 – 110 quadrillion kilometers and six times human biomass
00:11:15 – What a quantitative ecologist actually does
00:13:53 – Trade, lipids, and 30 percent of a plant's nitrogen
00:16:31 – What people get wrong about soil
00:18:27 – The pipeline: 34 satellite layers, random forest, Earth Engine
00:21:02 – From length to weight: effective radius and the robot named Prince
00:25:41 – Croplands and a broken 450 million year symbiosis
00:31:40 – Rights of nature and getting predictions accepted as evidence
00:37:10 – Where to find SPUN and Justin
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What does it actually take for an AI to navigate you through the real world, without a screen and without a camera running the whole time?
In this episode of the Spatial Stack, Matt Forrest sits down with Sean Gorman and Pramukta Rao, the co-founders of Zephr, to unpack how they ground large language models in location. Sean and Pramukta spent twenty years building startups together, from GeoIQ to Snap's visual positioning work, and at Zephr they walked away from the camera and went back to the sensors already in your phone.
They get into why the blue dot on a map breaks down the moment you stop looking at a screen, why language models are bad at spatial reasoning like left, right, and across the street, and how they fix it by doing the geometry first and handing the model clean language. Instead of training ever-bigger foundation models, they push a small model and well-structured data down to the edge so the conversation stays fast.
In this episode, we cover:
- Why they left visual positioning and AR cameras behind after Snap
- Cooperative positioning: getting survey-grade accuracy out of commodity phones
- GNSS and the urban canyon problem (3 meters to 50 meters and back)
- Beyond the blue dot: building a first-person, egocentric experience
- Why LLMs struggle with geometry, and what context engineering solves
- Small models at the edge vs giant foundation models
- Overture Maps, GERS IDs, and conflating POIs with imagery to "agree on reality"
- The grounding service: MCP, REST, and Opus or Gemma on device
- Conversations about place as a new geospatial primitive
Whether you build with spatial data, work on AI navigation, or just want to see where location and LLMs are heading, this conversation is your field guide.
Connect with Zephr:
Website: https://zephr.xyz
Sean Gorman (LinkedIn): https://www.linkedin.com/in/sean-gorman-93a79
Pramukta Rao (LinkedIn): https://www.linkedin.com/in/pramukta/
Zephr (LinkedIn): https://www.linkedin.com/company/zephr-xyz
00:00:00 – Intro and twenty years of startups together
00:04:05 – Why they walked away from cameras and AR at Snap
00:04:54 – Commodity sensors and cooperative positioning
00:07:15 – GNSS 101 and the urban canyon problem
00:10:56 – Beyond the blue dot: an egocentric experience
00:13:37 – Why LLMs are bad at left, right, and across the street
00:18:19 – Context engineering and the retrieval problem
00:22:03 – Small models at the edge vs giant foundation models
00:30:09 – Collective memory: OpenStreetMap, Mapillary, Overture
00:32:08 – Conflating POIs with imagery to agree on reality
00:35:36 – The grounding service: MCP, REST, Opus or Gemma on device
00:38:37 – What's next: conversations as a new geospatial primitive
00:42:22 – Where to find Zephr
📊 FREE: The Modern GIS Skill Map
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🚀 Join The Spatial Lab:
Stop guessing at your career path. Get direct mentorship, advanced training, and a roadmap to these high-value roles inside The Spatial Lab.
👉 https://forrest.nyc/spatial-lab/
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In this episode of the Spatial Stack, Matt sits down solo to work through a fight that broke out across Reddit and LinkedIn last week: is GIS dying, or is it just changing its name?
It started with a GIS manager who argued the field is alive, pointing to a friend who landed a $200,000 job building autonomous systems, a role where GIS never appeared in the title or the description. The comments pushed back. If the keyword for our whole profession barely returns jobs anymore, is the field really growing?
Matt's answer is that both sides are right. The work of spatial is expanding into data engineering, software, and product roles. The GIS title is contracting at the same time. It's one trend seen from two directions, the same way geology departments quietly became geoscience without the work ever changing.
He makes the case that the title was never the skill. Spatial intuition is, and it's the thing that transfers into higher-paying roles that don't carry the GIS label. Then he closes with a challenge: describe who you are and what you do without using the words GIS, spatial, or geospatial.
Whether you're job hunting, stuck in the technician trap, or an employer who wants this skill set but doesn't know what to call it, this conversation is about how we position the work going forward.
---
📊 FREE: The Modern GIS Skill Map
The 5 skills that actually matter in modern GIS (and what you can stop learning). Based on a survey of 1,400+ geospatial professionals.
➡ Get the free training + PDF guide: https://forrest.nyc/go/training/
CHAPTERS:
00:00:00 – The Reddit post that started it
00:01:00 – Two views: the work is growing vs. the title is shrinking
00:02:34 – Why "stay positive" doesn't pay the rent
00:03:33 – Spatial is special: what actually transfers
00:04:53 – The geology-to-geoscience analogy
00:05:54 – The title of GIS was never the skill
00:07:09 – The technician trap and where the salaries moved
00:08:18 – Listener comments: spatial judgment, the map as interface
00:10:32 – What to do now: SQL, Python, and cloud-native beyond the toolbox
00:11:51 – Building a portfolio on LinkedIn
00:13:22 – The Spatial Intuition Challenge
00:15:32 – Put your face on it: make it a video
CONNECT WITH ME
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🌐 Website: https://forrest.nyc