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LiDAR collection is pretty dense from a data perspective. When I was working with helicopter collection teams we would regularly collect 1TB of point data per d

LiDAR collection is pretty dense from a data perspective. When I was working with helicopter collection teams we would regularly collect 1TB of point data per day at around 120 points per square meter. Based on the density of the canopy in Central America, the teams are probably using a density greater than that, and are using "multiple return" depth mapping so that they can see through the forest. Processing LiDAR data is also quite expensive in terms of the hardware required and expertise of the people needed to correct the data back at the office. Typically LiDAR processing workstations have around 128-256 GB of RAM and a large RAID array of SSDs to quickly perform corrections interactively. After the initial correction, most of the data is thrown out or "filtered" down to just the points of interest to save on space. Since it's quite easy to end up with hundreds of TBs worth of point data within a few months of collection. If the team is using colorized LiDAR, orthographic, and oblique images then that can take up even more space. So the short answer to why more of the world hasn't been mapped with LiDAR techniques is money, time, and storage space. But with self driving cars now making LiDAR more prevalent, and storage space becoming more affordable every year, mapping whole regions with LiDAR is a more reasonable task. NOTE: One of my former jobs was working with aerial LiDAR collection teams to manage the data and processing of the collected assets. This was around 2012 so some of the numbers may have changed since then.

bradneuberg 9y ago
Perhaps neural networks can help with filtering and segmenting the point clouds as well?
52-6F-62 9y ago
Thanks, this is the kind of information I was curious about receiving in a concise digest. So ultimately it sounds like I have to wait a decade or so before we can really proliferate, and to speed it up need a few more eccentric billionaires to get into funding some cool projects. I'll use your information as jumping points to find out more.
- Dangeranger 9y ago
  My hopes lie with the open sourcing of in-vehicle processing hardware and software that is being used within self driving cars. As of today my understanding is much of that is part of the "secret sauce" of companies like Waymo and others. If it were possible to apply kinematic geo-correction along with point filtering and feature detection during collection then a lot of the "heavy" data could be reduced down to what is just needed for human verification. If you want to start your investigation with existing projects you could have a look at what the United Kingdom is doing with their government LiDAR data sets[0][1]. [0] https://www.gov.uk/government/news/environment-agency-uncovers-landscape-with-laser-mapping https://www.gov.uk/government/news/environment-agency-uncove... [1] http://vterrain.org/Locations/uk/ http://vterrain.org/Locations/uk/
  - 52-6F-62 9y ago
    Brilliant! Thank you. I wonder now if Canada has any projects remotely similar occuring
- deleted 9y ago
  [deleted]
- Scooty 9y ago
  Maybe the technology will become accessable enough that everyone with a smart phone can start finding and destroying archaeological sites.
  - 52-6F-62 9y ago
    Well, username kind of checks out. I like the tech because of its ability to prevent the destruction of archaeological sites while still allowing for discovery that would otherwise require an immense amount of digging and other labours.
deleted 9y ago
[deleted]
mcbits 9y ago
If my hasty math is in the ballpark, the raw data for 500 trillion square meters would be a few hundred petabytes. Not cheap, but cheap enough that I would guess the cost and logistics of acquiring the data are much more of an obstacle.
- Dangeranger 9y ago
  Yes that is true, logistical support and processing have considerable costs. For aerial LiDAR collection via helicopter you're looking at about $20,000 per day of onsite collection including the helicopter team, insurance, and support. That gets you high density low altitude assets, not including the processing and storage costs. It's cheaper to fly with a fixed wing aircraft, but you will typically get lower density assets and the possibility of obscured imagery due to cloud coverage because of the higher collection altitude. However the advantage is you're able to cover a wider collection swath with each pass, and it's a lot easier to fly a fixed wing vs. helicopter so the pilots are cheaper.
  - patrickg_zill 9y ago
    How much would the total weight be for the lidar equipment? I wonder if drones would be able to significantly reduce the price.
    - bobsil1 9y ago
      Met a Cal archeology ass’t prof doing this, quadcopter-mounted lidar.
    - Dangeranger 9y ago
      That depends a lot on the density of point coverage you need. Most LiDAR receptors weighed between 100-300lbs five years ago. They have become much smaller now, again due to self driving cars. However I am not sure that the hardware which is suitable for self driving applications would be "survey grade" appropriate for forest canopy and ground truth mapping. I'm also not sure what the power requirements of the newer LiDAR arrays are, but the weight for batteries is significant as it directly impacts your time "in the air" between ground support stations. In a helicopter you can power all the instruments off a DC power supply from the turbine. Also typically you want an absolute vertical accuracy of +/- 5cm during flight in order to confidently map the surface features below foliated vegetation cover. This requires quite specialized differential GPS equipment as well as a radio/cellular connection to a commercial GPS ground station network. With the improvements in GLONASS/GALILEO constellations maybe the ground networks are not as critical anymore.

bradneuberg 9y ago

Perhaps neural networks can help with filtering and segmenting the point clouds as well?

52-6F-62 9y ago

Thanks, this is the kind of information I was curious about receiving in a concise digest. So ultimately it sounds like I have to wait a decade or so before we can really proliferate, and to speed it up need a few more eccentric billionaires to get into funding some cool projects. I'll use your information as jumping points to find out more.

Dangeranger 9y ago
My hopes lie with the open sourcing of in-vehicle processing hardware and software that is being used within self driving cars. As of today my understanding is much of that is part of the "secret sauce" of companies like Waymo and others. If it were possible to apply kinematic geo-correction along with point filtering and feature detection during collection then a lot of the "heavy" data could be reduced down to what is just needed for human verification. If you want to start your investigation with existing projects you could have a look at what the United Kingdom is doing with their government LiDAR data sets[0][1]. [0] https://www.gov.uk/government/news/environment-agency-uncovers-landscape-with-laser-mapping https://www.gov.uk/government/news/environment-agency-uncove... [1] http://vterrain.org/Locations/uk/ http://vterrain.org/Locations/uk/
- 52-6F-62 9y ago
  Brilliant! Thank you. I wonder now if Canada has any projects remotely similar occuring
deleted 9y ago
[deleted]
Scooty 9y ago
Maybe the technology will become accessable enough that everyone with a smart phone can start finding and destroying archaeological sites.
- 52-6F-62 9y ago
  Well, username kind of checks out. I like the tech because of its ability to prevent the destruction of archaeological sites while still allowing for discovery that would otherwise require an immense amount of digging and other labours.

deleted 9y ago

[deleted]

mcbits 9y ago

If my hasty math is in the ballpark, the raw data for 500 trillion square meters would be a few hundred petabytes. Not cheap, but cheap enough that I would guess the cost and logistics of acquiring the data are much more of an obstacle.

Dangeranger 9y ago
Yes that is true, logistical support and processing have considerable costs. For aerial LiDAR collection via helicopter you're looking at about $20,000 per day of onsite collection including the helicopter team, insurance, and support. That gets you high density low altitude assets, not including the processing and storage costs. It's cheaper to fly with a fixed wing aircraft, but you will typically get lower density assets and the possibility of obscured imagery due to cloud coverage because of the higher collection altitude. However the advantage is you're able to cover a wider collection swath with each pass, and it's a lot easier to fly a fixed wing vs. helicopter so the pilots are cheaper.
- patrickg_zill 9y ago
  How much would the total weight be for the lidar equipment? I wonder if drones would be able to significantly reduce the price.
  - bobsil1 9y ago
    Met a Cal archeology ass’t prof doing this, quadcopter-mounted lidar.
  - Dangeranger 9y ago
    That depends a lot on the density of point coverage you need. Most LiDAR receptors weighed between 100-300lbs five years ago. They have become much smaller now, again due to self driving cars. However I am not sure that the hardware which is suitable for self driving applications would be "survey grade" appropriate for forest canopy and ground truth mapping. I'm also not sure what the power requirements of the newer LiDAR arrays are, but the weight for batteries is significant as it directly impacts your time "in the air" between ground support stations. In a helicopter you can power all the instruments off a DC power supply from the turbine. Also typically you want an absolute vertical accuracy of +/- 5cm during flight in order to confidently map the surface features below foliated vegetation cover. This requires quite specialized differential GPS equipment as well as a radio/cellular connection to a commercial GPS ground station network. With the improvements in GLONASS/GALILEO constellations maybe the ground networks are not as critical anymore.