Ask for an uncompressed or lossless image in addition to any lossy, compressed images they provide. This can make it difficult to precisely locate features on the map, since edges may spread out over several pixels. One drawback of image compression, especially the wavelet compression used by MrSID imagery, is that it can produce ringing artifacts around the edges of features. Orthoimages are large files, and you may receive a file that has been compressed to reduce its file size. Your contract with the imagery provider should specify the level of accuracy to expect across the entire image. Then we sketch over the image using normal AutoCAD drafting tools. What I am trying to do with the images is export them with the georeferenced data attached and import them to Google Earth Pro. They will also add the georeferencing data, the calibration points that allow ExpertGPS to determine the latitude and longitude of every pixel on the image. For many of our projects, we begin by creating exhibits by importing aerial photography from existing georeferenced TIFF files using AutoCAD Map (actually Civil3D and/or LDT). I have aerial view images (.TIFF) which I have georeferenced using ArcMap 10.4. Overhead imagery needs to be ortho-rectified by the imagery provider to remove the distortion caused by the aerial camera not pointing straight down when the photo is taken. The accuracy you get in ExpertGPS depends on the quality of the ortho-rectification done by the imagery provider and the correctness of the calibration points (tie points) given in the GeoTIFF or. If they don’t, there are free programs to extract a. tfw calibration file with the GeoTIFF – this would be standard if they were providing imagery for use in ArcGIS, so they should be used to it. It should be relatively painless for the consultant or the imagery provider to also provide a. ExpertGPS will treat it as an uncalibrated TIFF, meaning you’ll have to do the calibration by hand. Last but not least…when importing an image to ExpertGPS what format would yield the absolute best accuracy we could hope for? How to use GeoTIFF imagery in ExpertGPS?ĮxpertGPS doesn’t have the ability to read the projection and georeferencing data out of a GeoTIFF at this time, although it’s high on my list of to-do features for GIS users. raster files (as JPEG or GeoTIFF) plus a KML file that references them. tif files with the georeferencing information included. Export the data from ExpertGPS (File -> Export -> Save As -> Enter) as a. I have georeferenced a bunch of historical images and I want to export them as. My question to you is does ExpertGPS software support the beforementioned format and or if there is a better format to employ in your opinion.Īs a backup thought I have requested we receive the image in various formats to make sure all of our software would be compatible with it…. Kmz to shapefile converter All of these file formats, at the very least, store. If the image is a geotiff or MrSid, the image will already be. It is my humble attempt to not parrot the "party line.The District is considering the purchase of a new GEOTIFF aerial image of the district boundaries for mapping of the infrastructure…the consultant we have been in contact with is advising us to purchase the image in this format for its exceptional horizontal accuracy. I apologize for looking for very specific answers to very specific questions. (Other than the friend of the guy next door to the brother-in-law of a guy at work.) Is there any direct, hands-on, experience by any respondent in this thread. I didn't see a claim of such capability (SHP file transfer to Topo 7) on that referenced web page. load topo60c Z2 topo60c R2 topo60cR filename2 datafile ( topo60c.tif ) geotiffwrite (filename2,Z2,R2) The values in the data grid range from -7473 to 5731. So as noted above, Expert GPS, $50, will open SHP files and then save as GPX which can then be taken into TOPO 7 for transfer? My true intentions are also to be helpful with factual data. Please, my apologies if I've given the wrong impression regarding my intentions. I was just trying to be helpful to another GPS user by passing along other less expensive or free alternatives instead of strictly sticking with the "party line". No P.M., but "Delormers" do get a little "testy" when anyone refutes their "Talking Points". There are other softwares that will open SHP files and then save as GPX which can then be taken into TOPO 7 for transfer. In spite of what Delorme would like to have you think.
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