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Arhanghelul

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Everything posted by Arhanghelul

  1. Arhanghelul
    I have a multi-temporal NDVI package of raster images (100) and each image represents the monthly-annualy values of the NDVI for a large geographic region (28 april 2000, 15 may 2000, 24 july 2001, ...etc). I would like to export the rasters to an Excell table that should contain: date of image aquisition, a specific geographic region and the NDVI values for that region of interest. The values should be averages, minimum and maximums. With this table, I would like to make some statistical analysis. So, how can I do this job, by using ArcGIS or any other software ? Thank you. Arhanghelul
  2. Arhanghelul

    OpenPilot

    Arhanghelul replied to Lurker's topic in GeoHardware

    what about 3DR Pixhawk version 2 ? and the new drone models Solo from 3DR and Phantom 3 from DJI ?
  3. Arhanghelul
    I have a question for those who use UAV drones: what type of drone is better for geomorphological studies ? Let's say that I would like to map a landslide or multiple landslides. Should I use a fixed-wing or a multirotor (ex: quadcopter) UAV for this type of field research ? I know that there are different types of landslides, some of them can stretch only on a few slopes (1-5-10 ha), or hundreds of land surfaces. So, what type of UAV should I use ? Thx. Arhanghelul
  4. Arhanghelul
    Yes, is true. The errors will increase when you pansharp raster layers that have bigger resolution differences (ex: IKONOS, QuickBird and WV2 they have 1:4 spatial resolution differences). For the Landsat 7/8 the ratio is smaller, 1:2 (15 m panchromatic band, 30 m multispectral) so erorrs should be smaller. It also depends on what pansharpening method you use. Try different techniques. If you want to classify a pansharped image, a better alternative solution to the traditional per-pixel methods - supervised and nonsupervised (Maximum Likelehood, ISODATA, etc) would be an OBIA classification. OBIA is less sensitive to false pixels because it first creates image objects (poligons) and then it classify these objects, rather than individual pixels. Theoretically, a pansharped image should produse better classification results when using OBIA. eCognition and ENVI EX are the most common OBIA softwares. Arhanghelul
  5. Arhanghelul
    Me, i use 3 softwares : ERDAS, ArcGIS, and sometimes PCI Geomatica. Here you can read a step-by-step tutorial for mosaic in ERDAS: http://web.pdx.edu/~nauna/TourGuide9_1.pdf Also, you can find many video tutorials on YouTube.
  6. Arhanghelul
    You are one of the best users on this forum. Good luck Darksabersan, my friend !
  7. Arhanghelul
    yea, some alien visitors could have released, accidentaly, some methane gas after eating beans or drinking Coca-Cola
  8. Arhanghelul
    Where can I find an ENVI extension for topographic correction ? I tried to apply topographic correction on a mountain region using Landsat image and ASTER GDEM 30 m in ERDAS ATCOR3 module, but the results are very bad. I need some alternatives or I will skip this correction.....
  9. Arhanghelul
    ASTER has 5 thermal bands with 90 m spatial resolution (day and night). Landsat 5 TM has 1 thermal band (original 120 m was transformed by USGSS to 30 m spatial resolution) Landsat 7ETM+ has also 1 thermal band (original 60 m transformed by USGSS to 30 m resolution, but after 30 april 2003 all L 7 ETM images have diagonal strips; also there are some night thermal images in the archive). Landsat 8 OLI has 2 thermal bands (original 100 m transformed by USGSS to 30 m spatial resolution) but, for now, these bands have a problem with calibration (last I checked this). You can find more information about these satellites, algoritms and applications on Google search.
  10. Arhanghelul
    I think (I am not an expert) that you should also try to determine/estimate the number of vehicles travelling on each road, wich should correlate with the number of Deer accidents. And also, maybe you should know the number, age and sex of the Deer population. I assume that the Deer habitat is fragmented by the road network, no ?
  11. Arhanghelul
    I must say that it was my mistake. The DEM used in ATCOR3 must be Signed-integer 16 bits. Now, everithing is working ok. Sorry ! ERDAS is a good software.
  12. Arhanghelul
    I also have a problem using ATCOR 3 in Erdas 2014. When the software calculates the 4 output files from the DEM necessary for terrain correction (slope, aspect, sky view and shadows), the processing stops at 99% for sky view raster generation. I don't understand. The first 2 rasters (slope and aspect) are ok, but when it reaches to sky view raster processing, it stops. Stupid software......
  13. Arhanghelul
    There is a strong competition between airborne images and satellite images. If the companies that operate satellites want to stay in business, they must offer very high resolution images. And I think that there are already some facial recognition systems from sattelites, and maybe even more...... Big Brother is watching !
  14. Arhanghelul
    Hmmmm, very sad.......
  15. Arhanghelul
    Yes, probably you are right. A spatial resolution of 1.5 m makes SPOT 7 a high resolution satellite. But not a very-high-resolution image provider, such as WorldView-2 (0.5m). SPOT 7 will be added to the SPOT constelation of Astrium, increasing the posibility to produce more satelitte images in a shorted time period. Still, these images can be used for agriculture mapping, forest mapping, etc. Application that don't necessary need high-resolution images. But now, let's wait for the prices list of the new SPOT 7 Here, some technical details: http://www.astrium-geo.com/files/pmedia/edited/r18072_9_spot_6_technical_sheet.pdf
  16. Arhanghelul
    Another great news for the remote sensing community: SPOT 7 was launched from India and is now on orbit ! http://www.spacenews.com/article/launch-report/41070india%E2%80%99s-pslv-rocket-lofts-airbus-spot-7-satellite This will be a great source of satellite images (but not for free )
  17. Arhanghelul
    Can someone share with me tutorials about how to create a web-application, following my ideea ? Something descriptive, step-by-step, easy to understand. Thx.
  18. Arhanghelul
    If NDVI values are lower that 0 (-0.1 to -1) we have water bodies. The emissivity value for water is 0.995. So, I think that the NDVI threshold should look like this: if NDVI is under 0 (negative values), then we have water > emissivity for water is 0.995 if NDVI is between 0 and 0.2, then we have bare soil > emissivity for bare soil is 0.97 if NDVI is > 0.5, then we have vegetation > emissivity for vegetation is 0.99 if NDVI is between the values 0.2 and 0.5 ( 0.2 ≤ NDVI ≤ 0.5), then we have a mixture of bare soil and vegetation > emissivity is calculated by the equation of Sobrino method
  19. Arhanghelul
    It looks very complicated for me, as a beginner.
  20. Arhanghelul
    You can also export the classification from eCognition as a raster image. And then you can open the classified raster in ArcMap.
  21. Arhanghelul
    in ENVI and ERDAS you can use a sub-pixel endmember classifier (ex: SAM). Yes, is difficult, probably impossible to separate some classes in urban areas based only on spectral values. An OBIA approach, using eCognition can produce better classification results compared to traditional per-pixel methods (ex: maximum likehood and ISODATA). This is because eCognition creates object segments, and you can use the shape, texture or position of the objects in you satellite image for superior classification results. Conclusion: first, try to use a sub-pixel method, with a neural network method, and if the results are not satisfactory, try to use eCognition. You can find the eCognition software here, on this forum, with the crack/medicine, Give a search on the forum.
  22. Arhanghelul
    Good news for remote sensing industry and for the satellite images users. WorldView-3 images will be accessible for public (not for free ) starting from may 2015 ! WorldView-3 images will have the best spatial resolution existing, for civilian customers: 0.31 m for b&w band and 1 m for multispectral bands. http://www.spacenews.com/article/civil-space/40874us-government-eases-restrictions-on-digitalglobe I belive this event and future events for new and better high-resolution satellite images developments will force also the image interpretation and information extraction softwares to develop. New or improved techniques such as Object-based Image Analysis (OBIA- eCognition) will probably benefit from this new era of remote sensing industry. Softwares and applications that will better incorporate Remote Sensing with GIS and statistics will be forced to develope to keep up with technology evolution.
  23. Arhanghelul
    It looks like there is a competition between USA and ESA for new satellites or a continuity of programs. Maybe even some cooperation, now when they have money problems. http://www.spacenews.com/article/civil-space/40841nasa-official-a-landsat-8-clone-would-cost-more-than-650-million About the Copernicus program of ESA, it might have some problems because of the Airbus company ( money interests, again ): http://www.spacenews.com/article/civil-space/40817airbus-seeks-new-terms-on-data-relay-contract-with-esa
  24. Arhanghelul
    youtube is full of tutorials about how to make an accuracy assessment. Just use search on youtube. Thea ideea is very simple: you must select testing samples (from in-situ or from the raster image, and the value class of these points are compared by the software with the class values of your classified raster) and then the software will generate the confusion matrix (a table that will show you the total accuracy of your classification and the accuracy for each land use/land cover class)
  25. Arhanghelul
    Yes Lurker. Some will lose, others will benefit from this situation. I hope these changes will increase the remote sensing products and applications worldwide, whit benefits for all of us.
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