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nadar last won the day on November 20 2013

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About nadar

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    Senior Instructor

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  1. Hello could you please re-activate my status ? Thanks
  2. Is there a possibility to find the location of a image extracted from Google Earth ? I received a few images obtained by screen copy of Google Earth. The scale bar is included in the image, but not the coordinates nor the orientation (I assume it's North up). I only have a vague indication of the region. Is there a solution to analyse the GE database using some image matching algorithm ?
  3. If the subject doesn't move too much (no wind on the leaves, etc.) and the camera is fixed, it will probably work, but don't expect extraordinary results (because of the ultrawide lens, resolution is lower on the border of the images. If the subject or camera are moving (including vibrations), then the rolling shutter will be a severe limitation. For a serious project, I will rather use a compact camera with a "normal" lens and a global shutter.
  4. If you use spectral properties to classify, they should be as pure as possible. Visual interpretation using your brain is much more sophisticated than any computer-based classification, because it constantly switch between a local analysis (mainly texture and shape) and a global analysis (scene structure). Having a (big) computer slowly driving a car (in moderate traffic and on good roads with plenty of road signs) is one thing. Driving madly a junk car in Instambul traffic jams is another story. I'm not saying a computer is always more stupid than a turkish taxi driver, but as far as scene a
  5. This one works: http://www.asprs.org/a/society/committees/standards/ASPRS_Positional_Accuracy_Standards_Edition1_Version100_November2014.pdf
  6. "error 404. Not Found. Sorry, but that page is lost." Any idea, ?
  7. I tried. I only found a solution to put all selected points to the same elevation, but not to add or remove the same value to each individual point (to rise up a roof for instance) May be I shoud try exporting a portion of the cloud and reimporting it at another position ?
  8. I'm looking for a solution to modify the elevation of selected points in a .LAS or .PLY points cloud. I want to simulate an increase or decrease of the height of selected objects (trees, buildings, etc.). I dont want to change their colour. The ability to move a selected group of 3D points would also be useful. I know how to do this in a mesh generated from the cloud, but I have to fully preserve the details of the cloud. can somebody share some ideas or indicate a software compatible with these requirements ? Thank you in advance
  9. I agree with you, on some satellites, the difference of resolution between pan and multispectral becomes ridiculous. Keep in mind that a ration 1:4 means you get 16 Pan pixels for one multispectral ! High contrast objects completely "smear" on the neighbours. I understand for marketing reasons, producers want to announce the highest figures, but.... I'm not even talking about the effective resolution of these images. If you want, you can resample a Landsat TM image to 10 cm ! I don't thin an algorithm will be able to reconstruct high res multispectral images suitable with classification.
  10. Thanks a lot. I have some readings for a while. I will come back later
  11. In Montana, I think you can upload your own raster maps ("custom maps"). I did it, but the management of memory is not very efficient, and as soon as you get a few maps, you get 'insufficient memory" errors, even if you have plenty room on your memory card. Global Mapper has interesting possibilities to export either vector data or raster maps to Garmin devices
  12. Does somebody have a good reference on - practical results of DEM generation using various types of satellite imagery - the relation (if any) between spatial resolution) and the accuracy (in elevation) for derived DTM/DSM - the same question about airborne LiDAR data (relation between points density and accuracy). (I'm preparing a project where DEM accuracy is critical (flooding) and we are hesitating between satellite and airborne LiDAR All advices and experience are welcome !
  13. Publishing such info without a price tag is useless and quite stupid. Users are not cows waiting to be milked.
  14. Very compact motion and position sensor. It uses a MEMS inertial system (INS) to measure angles and accelerations combined with a GPS to measure positions and speed. Xsens MTI-G-700 (purchased in march 2013) specs: http://shop.xsens.com/shop/mti-g-100-series/mti-g-700-gps-ins/mti-g-700-gpsins-2a5g4-dk Provided with software development kit and carrying case Connection to PC via USB cable (4m length) GPS antenna with strong magnetic mount: cable length 3+5 m size: 58x58x22 mm. Weight 58g. Software: MTmanager (provided with full licence and recent updates) is used to
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