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Art409 last won the day on September 16 2016

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  1. Hi There. I'm back. Can you give me access to other forums? Regards. Art
  2. Hi Guys, Hi Lurker. After some time away of the geospatial stuff i'm back. ¿could you reactivate my account? Thanks
  3. Hi Mapper310! One question: "Resolution" of what? The same word uses for different tipes of things. In general remote sensing, "resolution" refers to the ability of discrimnate different things. Spatial resoulution, Spectal resolution, Band resolution, Dynamic resolution, time resolution, and goes on...
  4. Thanks Lurker!. I don'y want to sound unpoilte. Sorry if my english limited me in that way pasfan01. The key is that the soft, it's an implementation of some tehoretical algorithm. Sometimes, we coud use or adapt that algorithm for a different prupose, but sometimes... is usefull. Knowing the photogrammetric tehory, I advise that using Agisodt for pushbroom (or barridors like Landsat TM and ETM) CAN'T perform fine. Usually in remote sensig DTM there is not not an inmediate risk for the user, But this sound to me like some one using an enginieering software designed for bridges structural analysys, trying to calculate the dome of a stadium, What I mean with "Can' perform fine"?? I state that the deliverable that you can obtain with cartosat-1 and Agisoft, will be less accurate that any ASTER DTM, OR SRTM (Ok SRTM data was taled in 2000, but Aster is still operative) I'd out of spatial imgining for a couple of years, so I don't know what images are available today. Art PS: If any one want an explanation about why the movement of the camera (180km) is relevant, I can explain that
  5. LOL. Here goes one example of "theoretical stuffs". Why don't try to build a satellite instrument to see earth surface freflectance in ultraviolet o shoter wavelegnghs? Answer: it''s IMPOSSIBLE to see that from space due atmospheric absortion!!! What you call "theoretical stuffs" is the cause that we need the soft. "Discover" dosen't mean "ignore" knowledge. Belive me, maybe the soft allow you to get some result. But these result is a useless. I hope your doctor don't sahre your point o view!
  6. Happy new year!. Agisoft solution is for frames. 1 frame, exterior orientarion (aka Camera in agisoft) A landsat 7 scene got a aprox 180km along track, that menas the camera moved more than 180Km. ¿You took that as a simple scene?
  7. If you found please let us know. I'd looked for months a no result yet.
  8. Very nice Lurker! But i'd go for the Firefly6 Pro! https://www.birdseyeview.aero/ ok. weights lots more, but... poerate from anywhere and productivity is unmatched!
  9. nnico. that's beyond my league, but... whay version of carry map you are working with?
  10. Hi Laura: You want to calculate tree heigths? Or just want a DEM? Some info now: Optical data can't go below trees or any other coverage. You just can use patches with crear view o terrain to extract DEM LIDAR can reach the ground going trough "holes" between foliage, in a way that we can ASSume the last echo as a terrain echo. Very dense foliage don't allow lidar reach ground. Radar... (ouch!) I'n out of date about SAR new satellites, or aerial ones., but: REMEMBER, inside the SAR minimal data (let's call it a PIXEL, for now) you got a lot of responses added from everithing that reflect te signal. Note: Landstat 8 is no good for stereo, so LANDSAT8 discarded for DEMs Art
  11. Landsat-1 (Originally named ERTS-A for Earth Resources Technology Satellite); Landsat-2 (called ERTS-B until few time prior to launch, and Landsat 3; and also Spot (Satellite Pour l’Observation de la Terre: Sattellite for Earth observation) prime focus was in terrestrial natural resurces (soils, crops, etc) Landsat was aimed to for geology an Spot for agriculture) Due communication limitations at that time (we talk about hundreds of megabytes by minute in the ’70s) they chose limitated number of bands to survey different spectral signatures, and due just few things got differences in blue band (beyond water) they chose to carry a more usefull close infrared band than the blue one. Regards. Art
  12. ajaysbharadwaj Nice issue do discuss! A) SOURCE DATA yes, Google Earth uses mostly SRTM, but in someplaces uses other sources. We don't know where or the source quality, so.. we end with a DEM with unknow quality. "NASA has released a void-filled version of the Shuttle Radar Topography Mission digital elevation model, known as "SRTM Plus" or SRTM NASA Version 3. SRTM Plus uses SRTM Version 2 (see below) where the radar interferometric method was successful (not void). Most voids are filled with elevation data from the ASTER GDEM2 (Global Digital Elevation Model Version 2)." (see http://www2.jpl.nasa.gov/srtm/) Bayond that, you can search in your Area of interest for better accuracy/Resolution DEMS Interpolation ============ I strongly disagree with you. You took grid data. get XY points (manually), and then interpolate again to a grid!!! Why don't you just use Shuttle Radar Topography Mission (SRTM) Data in Surfer?? (here go how: http://www.goldensoftware.com/Newsletter/issue52s# ) Contours "look better" because: 1) you use less source data to interpolate (if you are use the more data points you are using interpolated points to interpolate, and if you use the same data ponits you work a lot more for the same results) and most important: 2) You interpolate with a smooth/stocatic method (Kriging), and using default parameters! You can use a lot of interpolation methods (In surfer, ArcGIS, or mostly any software) Linear, IDW, Krigin, NN, Spline, Trend, etc., with o without breaklines/barrers I ussually avoid use Kriging for terrian, beacuse tend to smoth terrian breaks. Why? ¡¡¡Nice and Smooth countous dosn't mean better acuracy!!! Ussually the oposite! Regards Art
  13. Sorry, but I don't understand the advantages over download the full SRTM data. https://lta.cr.usgs.gov/SRTM "SRTM 1 Arc-Second Global elevation data offer worldwide coverage of void filled data at a resolution of 1 arc-second (30 meters) and provide open distribution of this high-resolution global data set. Some tiles may still contain voids. Users should check the coverage map in EarthExplorer to verify if their area of interest is available. Please note that tiles above 50° north and below 50° south latitude are sampled at a resolution of 2 arc-second by 1 arc-second." You can donload fromUSGS's Eart Explorer http://earthexplorer.usgs.gov/ Data is also availabre from other sources, and in other formats Cherrs Art
  14. Hi Lurker! I'm sorry too for the late reply. As you I trying to classify UAV point clouds, and yes, Lidar derivates are different. Lidar got echo numer (or full wave proccesing), and Image derivates got 3 (or more) color bands. My main goal is extract buiding from cloud points, but I'm sure that I'm far behind your steps. I got soid theroetical background, but I almost got not time for test, (and I don't plan to trask/deliver anything 'till I'm not sure of the process) Please take a look to one or both "Lidar analyst" and "feature analyst" Looks promising Art
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