Getting started with the Fusion program and LiDAR data

Reports and articles related to remote sensing, LIDAR, GIS, and other mapping applications.

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James Parton
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Re: Getting started with the Fusion program and LiDAR data

Post by James Parton » Tue Mar 29, 2011 9:49 am

Cool! Now I can get into this LiDAR stuff!
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edfrank
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Re: Getting started with the Fusion program and LiDAR data

Post by edfrank » Tue Mar 29, 2011 10:03 am

Joe,

Yes it is accurate, but there are some caveats that require the results be ground-truthed. There are limits to the resolution of the data, so there is some averaging and extrapolation at this level on both the ground surface and tree tops. The LIDAR likely will not resolve the finest branches that make up the extreme top of the tree. It is measuring the distance between the tree top and the ground directly below the top, which might not be the same as the base of the tree. This is a particularly important variable on areas of steeply sloping ground. It works best on areas that are generally flat. But with all that being said, from what people have posted it appears to be a fantastic tool for scouting out an area looking for tall trees. You would still need to visit the site and determine the species of the tall hits and confirm their heights. For species that are not the tallest, the area still needs to be scouted and measurements made. If all the tall trees on a site are sycamores, the site still should be visited to measure other species and to look at species diversity, girth etc. So LIDAR a big thumbs up as a scouting tool, but sites still need to be visited, and if you are looking for old growth - the LIDAR tells you nothing about the age structure of a site. It could be a site dominated by young tall trees, while an older forest on a less ideal site may still be relatively short.

Ed
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Matt Markworth
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Re: Getting started with the Fusion program and LiDAR data

Post by Matt Markworth » Sat Mar 09, 2013 6:24 am

Steve,

Thanks so much for sharing your process on how to analyze the OGRIP files with Fusion. Your step-by-step explanation made it easy to jump in and get started.

So far I've used it for scouting purposes, but now I want to find the individual trees that caused the tallest hits. Utilizing the view of the terrain has put me in the right area, but I want to use latitude/longitude to ensure that I'm not misreading the terrain and that I'm actually in the right spot.

I haven't been able to figure out if Fusion can show the latitude/longitude of a specific point, but I've been able to find it using this method. If anyone knows how to pull latitude/longitude directly from Fusion, please let me know.

1) Use the LIDAR Data Viewer to pinpoint the tallest hit.

2) Select a very small area on the Fusion image that includes the tallest hit.

3) Right click on the Fusion image until the individual tree is visible.

4) Compare the Fusion image with maps.google.com and line up a couple landmarks, and match up the location of the tree. Use the “What’s Here” functionality on maps.google.com to find the latitude/longitude.
Or,
Compare the terrain on the LIDAR Data Viewer with the terrain on the USGS National Map Viewer. Place the cursor on the spot of where the tree would be on the USGS National Map Viewer and the cursor position will show the latitude/longitude.

5) For verification purposes, enter the latitude/longitude into the OGRIP site and make sure that the tree image matches the tree image that was on the Fusion image.

- Matt

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Steve Galehouse
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Re: Getting started with the Fusion program and LiDAR data

Post by Steve Galehouse » Sat Mar 09, 2013 11:16 am

Matt-

I've also tried to get lat/long co-ords directly through Fusion, without success. There must be a way to do so, as the viewer screen has a button for GPS values. I end up doing something similar to what you do, but I've found Big Birdseye images to be more helpful than google.maps. The tall trees in my area are nearly always associated with topography that readily relates the screen image to the actual location.

Steve
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Matt Markworth
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Re: Getting started with the Fusion program and LiDAR data

Post by Matt Markworth » Sat Mar 09, 2013 12:26 pm

Steve,

Sounds good, thanks again for the help and for the suggestion. For a site that I just checked, Google has leaves on and Bing has leaves off. The image from OGRIP has leaves off, which matches up nicely with Bing.

-Matt

Jimmy McDonald
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Re: Getting started with the Fusion program and LiDAR data

Post by Jimmy McDonald » Sun Mar 10, 2013 10:49 pm

Wow this could be amazing. Thanks for the instructions. I was able to get it to work. How would I go about getting info for MN or other states?

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Jess Riddle
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Re: Getting started with the Fusion program and LiDAR data

Post by Jess Riddle » Sat Mar 16, 2013 4:10 pm

Steve, Matt;

If your just interested in the highest points, there is a clunky way to get coordinates out of Fusion. Try Tools->Terrain model->describe terrain model then select the canopy height model that you're interested in. In the "Describe DTM" window that pops up, hit the "view elevation data" button. A new window should open with a contour map of your canopy height model. Increase the contour interval to slightly less than the tallest trees. You should then see a nearly blank map with a few small rings that indicate where the highest canopy is. Move your cursor over the tall tree area of interest, and the X and Y boxes will display the coordinates in the same units as the original LiDAR data.

Jess

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Matt Markworth
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Re: Getting started with the Fusion program and LiDAR data

Post by Matt Markworth » Wed Feb 19, 2014 8:01 pm

Jess Riddle wrote:Steve, Matt;

If your just interested in the highest points, there is a clunky way to get coordinates out of Fusion. Try Tools->Terrain model->describe terrain model then select the canopy height model that you're interested in. In the "Describe DTM" window that pops up, hit the "view elevation data" button. A new window should open with a contour map of your canopy height model. Increase the contour interval to slightly less than the tallest trees. You should then see a nearly blank map with a few small rings that indicate where the highest canopy is. Move your cursor over the tall tree area of interest, and the X and Y boxes will display the coordinates in the same units as the original LiDAR data.

Jess
Jess,

I just now noticed your reply, thanks!

Do you know how the X,Y coordinates can be converted to lat/long? I'm currently looking at some 158' LiDAR hits and other than trying to match up the image/elevation with google maps/bing maps/USGS, I don't know how to find lat/long.

Matt

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Rand
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Re: Getting started with the Fusion program and LiDAR data

Post by Rand » Fri Feb 21, 2014 10:17 am

Matt Markworth wrote:
Do you know how the X,Y coordinates can be converted to lat/long? I'm currently looking at some 158' LiDAR hits and other than trying to match up the image/elevation with google maps/bing maps/USGS, I don't know how to find lat/long.

Matt
After much yelling, FUSION manual mucking, and google bashing I figured it out. The LIDAR coordinates in Ohio are in a 'State Plane' coordinate system. This is a somewhat arbitrary set of coordinates set up for each state, most are in multiple zones:
SP-1.jpg
This site will convert them for you:

http://www.earthpoint.us/stateplane.aspx
SP-2.jpg
Which zone you are in is indicated by the 'N' or 'S' in the first character of LIDAR file names you download. Also, make sure you change the 'XY Unit of Measure' radio button to feet or you'll get la-la-land GPS coordinates.

Finally the 'Fly to on Google Earth' button will download a kml file that you can open in google earth as a quick sanity check.

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Rand
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Re: Getting started with the Fusion program and LiDAR data

Post by Rand » Fri Feb 21, 2014 11:18 am

Here's another method of zooming into high points:

1) Click on the 'Sample Options' button. In the resulting dialog click 'Subtract Ground Elevation from each return'. (If you don't, the measured heights will be in feet above sea level. The downside is that the LDV display ignores all terrain, and displays the canopy as laying across a flat plane, making it difficult to tell when tall returns are just short trees leaning out over steep drop-offs)
s-1s.JPG
2) Open the area of interest in the LDV viewer. Next right click in the viewer and turn on 'Measurement Marker' from the popup menu.
s-2.JPG
3) Right Click again and select 'Snap Measurement Marker...' > 'Move Measurement Marker to highest data point'.
s-3.JPG
At this point the Measurement marker shows up on the screen as a shaded cylinder. The X Y data readout at the bottom of the screen shows the location of the bold centerline of the cylinder. The actual high point within the shaded cylinder is highlighted with a white XYZ axis mark. Move the center point of the cylinder over this point by holding down the shift key and the using the arrow keys on your keyboard.

You'll also notice your scroll wheel doesn't zoom while the measurement marker is on. Hold down the control key and right click+drag up and down in the LDV window with the mouse instead.
s-4.JPG
Two other options I find useful in the LDV popup menu are

- 'Draw only points within measurement cylinder' - Will clean up the display a little when trying to zoom in on a given point.
- Personalities... > Fast Computer - Will show an aerial photo mapped onto the terrain surface (but not when the measurement marker is on).
- 'Marker...' - Allows you to change the size of the LIDAR dots on screen. Useful when selecting different sized areas to view in the LDV viewer.

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