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16

Yes you need to Georeference the images. The Exif data explains where the photo was taken, so it describes where your drone/camera was at that time and often many other values (heigth, bearing etc). QGIS and mapping packages work off a different method of locating the image and usually require a location of the center of the upper left pixel, knowledge of ...

9

So if I assume the following variables: x = camera sensor x size y = camera sensor y size f = focal length h = height above ground And I am looking for: ay = photo y ground distance ax = photo x ground distance Would these formulas work? making sure that I compare the proper units to the proper units. (h/f)*x = ax (h/f)*y = ay Does this make ...

8

I've done this before with success using the Photosynth Toolkit (http://www.visual-experiments.com/demos/photosynthtoolkit/), except instead of a drone I was hanging my head out of a small plane taking pictures of the downtown area of a small town. You could also check out Visual SFM (http://ccwu.me/vsfm/); I haven't used it but it seems to be another tool ...

7

Full Credit to Henri Eisenbeiß (Author) from the dissertation 1.1.1 UAV photogrammetry Extract: "The new terminology UAV photogrammetry describes aphotogrammetric measurement platform, which operates remotely controlled, semi-autonomously, or autonomously, without a pilot sitting in the vehicle. The platform is equipped with a photogrammetric ...

6

For ground control, you're going to want something easily visible from your UAV. Temporary GCPs may be good enough for your purposes. Personally, I've used weighted plywood painted with an arrow in bright colors like yellow and red. The tip of the arrow gives you a precise location to both set your RTK unit over and visually identify when georeferencing ...

5

I can confidently say yes. Add in some surveyed ground control points and you can easily get 10 cm positional accuracy. So far there are two big players that I have been using pix4d is by far the best but it is the most expensive it is really good for editing mosaics. Actually pix4d now has apps to directly work with your phantom and even has a free ...

5

Assuming you have attributes for the polygons for each type (clear cuts, young forest, etc), you can run the Dissolve tool in ArcGIS with this ‘Type’ column as the Dissolve_Field. This will aggregate all the features of each type. If you UNCHECK ‘Create Multipart features’ your result will be a single polygon for each contiguous feature of each type. ...

4

In Austria and Germany Karl Kraus taught remote sensing and photogrammetry and wrote several books which are IMO fundamental and very good for the understanding of this matter, despite the age of these books. Unfortunally he died in 2006. There is a translation made by Ian Harley and Stephen Kyle. Karl Kraus, Photogrammetry, Volume 1, 2007: Geometry from ...

4

fiducial mark are used to define the coordinate system of the photograph. With film photograph, the paper moves under the objective and can get further distorted during storage and development, so you need to localise the image on each frame. On the other hand, digital sensors are fixed, so you don't need any mark on the image to define the coordinate system:...

4

I've finally found a tool that does this. This task is referred to as mono-photogrammetry or monoplotting and involves referencing a single oblique and unrectified photo to a DEM to produce georeferenced data for use in a GIS. This is similar to photogrammetry, except you only have a single image. The WSL Monoplotting-Tool is specifically designed for this ...

4

Give RAPID for DJI a try. It will geo-reference and process up to 100 images from any DJI sensor or drone for free. The results are WGS84 Lat/Lon GeoTIFF format digital elevation models, point clouds and orthomosaic maps. Disclaimer: I wrote the software and dronemapper.com SaaS service. Thanks!

4

gdal_merge allocates memory for whole raster at once so it runs quickly for datasets that fit into memory. If it is not you case, use gdalwarp tool which does tiling so you can control how much memory does it use: gdalwarp --config GDAL_CACHEMAX 512 -wm 4096 merged.tif where GDAL_CACHEMAX is memory for IO cache and -wm is memory limit which controls the ...

3

To calculate a volume, you need the 3D Analyst extension. 3D Analyst has several ways to calculate volumes. All methods require the data to be in a projected coordinate system. You can use TIN or Terrain surfaces. Method 1: Surface Volume This method assumes one of the surfaces is a flat plane and the other surface varies. It can calculate volumes ...

3

We have created an webpage with a script that will perform the calculation for you: Aerial Camera Ground Footprint Calculator. You just have to enter the variables mentioned and click the Calculate button. Please note the calculator interface is in English, but the primary site language and explanations are in Spanish.

3

For looking at points in QGIS you could check out lastools and their las2shp tool. That would turn your 3d point cloud (in las format) into a vector point file. lastools even has a QGIS toolbox now for full integration. Edit: Check out http://opendronemap.github.io/odm/ as an open source alternative to agisoft. https://www.youtube.com/watch?v=e2qp3o8caPs

3

Opticks Image Segmentation Opticks is an open source Imagery Analysis Software. It will perform segmentation on an image and save the results to a Shapefile. The link has a short segmentation tutorial. The software runs on Windows 32/64, Linux and Solaris.

3

There is something better! Check this out: http://www.123dapp.com/. You can use 123Catch to combine many photo's into a 3D model. Then use 123Sculpt to make the model better! Alternately, try this stuff for a home-made solution: http://www.visual-experiments.com/ the guy who put it together has gone to work with Microsoft, so he's doing good things!

3

Open Aerial Map's wiki (http://openaerialmap.org/Processing) suggests GRASS GIS' i.ortho.photo and related modules (per Micha's suggestion). OSSIM http://trac.osgeo.org/ossim/ - probably best bet. http://www.digilab.uni-hannover.de/index.html - looks like it would require some development work to be useful http://www.orfeo-toolbox.org/otb/ - very active ...

3

Using the Trend tool does not work because it will only smooth the DSM surface, while what it is necessary is a DEM (bare-earth surface). What you want is a Canopy Height Model (CHM) (sometimes known as a normalized DSM) which is a raster expressing heights from objects relative to ground (i.e., all ground points/pixels are set to the same level, a ...

3

I found this page in the Pix4D documentation which states: Keypoints are points of interest (high contrast, interesting texture) on the images that can be easily recognized. The number of keypoints depends on: The size of the images. The visual content. A 14MP image will generate between 5'000 and 50'000 keypoints per image. And ...

2

this link describes the use of the open source software Palentier , but i don't know the accuracy supported with this suite, and if it could produce DEM or just stitched photos. i think the point cloud library could help too.

2

We have found the image segmentation model in Spring to be comparable to eCognition. Spring is a free remote sensing software developed by the Brazilian government.

2

There are successful solutions available based on eCognition, for instance: http://www.trimble.com/imaging/pdf/TM18_FINAL_INPHO.pdf eCognition offers the possibility to translate your mind model (why you see buildings in our images) into computer understandable code (= rule set). The eCognition Developer is the environment to create rule set. A good rule ...

2

There are several softwares for doing this. Here is a non exhaustive list : Commercial licence : Imagine Photogrammetry (= formerly LPS) This is very powerful but very expensive ENVI DEM module photoscan Not very expensive, but more oriented toward drone image processing, so not the best for satellite data Open source : Orfeo Toolbox Not tested for ...

2

Let me give you some suggestions: For SFM workflow you can use VisualSFM (http://ccwu.me/vsfm/). It is free for non-commercial use. Here you can also transform coordinates using GCP or GPS data in EXIF file of images/input gps file. The output of PMVS can be stored and opened in Meshlab. From there you can export .ply file (I guess should not be saved as ...

2

Some time has passed, the topic is still relevant since new software became available: Did anyone try out the NASA Ames Stereo Pipeline (ASP, http://ti.arc.nasa.gov/tech/asr/intelligent-robotics/ngt/stereo/)? The source code is on github. Furthermore, in the open source software Orfeo Toolbox (OTB, http://orfeo-toolbox.org) they offer "One-click DEM ...

2

I guess that your fish fence polygon covers several DEM grid cells. Normally you would extract DEM grid values to a point layer with a plugin tool like Point sampling tool. If you polygons are very small in relation to the DEM cells you could use the centroid of the polygon as a new point layer doing the Point sampling plugin tool on that point layer. With ...

2

I think the paper Application of RPC model for InSAR phase evaluation is good to start with and then you can continue with the references of that paper The paper Robust Estimating Three-Dimensional Ground Motions from Fusion of InSAR and GPS Measurements is another good resource This book can be a good resource, too. It's not completely relevant but ...

2

OpenDroneMap has some sample data. You can give it a try: OpenDroneMap

2

I think a way to do this is VisualSFM to do the matching of the photos (the stronger the GPU the better) and creating a dense point cloud and MeshLab to create a textured triangulated model from the point cloud. VisualSFM: http://ccwu.me/vsfm/ http://ptak.felk.cvut.cz/sfmservice/websfm.pl?menu=cmpmvs (cp. especially the 'Technology' site and the paper ...

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