Sorry for the mess...<div>I made an error because I thought that tiffs were RGB black and white but they are sigle band 1 bit images</div><div><br></div><div>I tried to use nodata values during vrt generation like this</div>
<div><pre class="fragment" style="font-family:monospace,fixed;font-size:9pt;border:1px solid rgb(196,207,229);background-color:rgb(251,252,253);padding:4px 6px;margin:4px 8px 4px 2px;overflow:auto;word-wrap:break-word;line-height:15px">
gdalbuildvrt -hidenodata -vrtnodata "0" test.vrt *.tif</pre></div><div><br></div><div>Then mosaic tiffs with</div><div>gdal_translate -of Gtiff -co SPARSE_OK=TRUE -a_nodata 0 -co NBITS=1 -co "TILED=YES" -co "COMPRESS=CCITTFAX4" -co "INTERLEAVE=BAND" -co "TFW=YES" "test.vrt" "test.tif"</div>
<div><br></div><div>Null overlapping areas still present in the output..</div><div><br></div><div>Where is my mistake?</div><div><br></div><div>Here is the gdalinfo for a tiff</div><div>*********************************************</div>
<div><div>Driver: GTiff/GeoTIFF</div><div>Files: 018131.tif</div><div> 018131.tfw</div><div> 018131.aux</div><div>Size is 7400, 6491</div><div>Coordinate System is `'</div><div>Origin = (2344486.561459757400000,5168752.558307543400000)</div>
<div>Pixel Size = (0.442006745841354,-0.442006746307015)</div><div>Metadata:</div><div> TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)</div><div> TIFFTAG_SOFTWARE=IrfanView</div><div> TIFFTAG_XRESOLUTION=57</div><div> TIFFTAG_YRESOLUTION=57</div>
<div>Image Structure Metadata:</div><div> COMPRESSION=CCITTFAX4</div><div> INTERLEAVE=BAND</div><div> MINISWHITE=YES</div><div>Corner Coordinates:</div><div>Upper Left ( 2344486.561, 5168752.558) </div><div>Lower Left ( 2344486.561, 5165883.493) </div>
<div>Upper Right ( 2347757.411, 5168752.558) </div><div>Lower Right ( 2347757.411, 5165883.493) </div><div>Center ( 2346121.986, 5167318.025) </div><div>Band 1 Block=7400x1 Type=Byte, ColorInterp=Palette</div><div> Description = Band_1</div>
<div> Metadata:</div><div> LAYER_TYPE=athematic</div><div> Image Structure Metadata:</div><div> NBITS=1</div><div> Color Table (RGB with 2 entries)</div><div> 0: 255,255,255,255</div><div> 1: 0,0,0,255</div>
</div><div>*********************************************</div><div> <br><br><div class="gmail_quote">2012/11/14 Pietro Rossin <span dir="ltr"><<a href="mailto:pierigis@gmail.com" target="_blank">pierigis@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">Ok<div>I made a test VRT and I applied your gdal_translate command.</div><div>It work and the result is a tiff with a weight of about the sum of the two test mosaiced tiffs.</div>
<div>But as you can see in this image</div>
<div><br></div><div><a href="http://www.flickr.com/photos/90029615@N05/8184720800/" rel="nofollow" link="external" target="_blank">http://www.flickr.com/photos/90029615@N05/8184720800/</a><br><br>the two tiffs have a white orizzontal stripe that separate them.</div>
<div>
This is because each tif to be mosaiced have a white frame and every frame overlap to "data" areas of adiacent images.</div><div><br></div><div>If I eliminate the 255 value from original tiffs the result is like this</div>
<div><a href="http://www.flickr.com/photos/90029615@N05/8184744636/" rel="nofollow" link="external" target="_blank">http://www.flickr.com/photos/90029615@N05/8184744636/</a></div><div><br></div><div>I tried using -a_nodata 255 in gdal_translate command but the result is the same white separation..</div>
<div><br></div><div>How can I set 255 values to nodata before mosaic each tiff?</div><div><br></div><div>Thank you very much for your help!</div><div>Pietro</div><div><br></div></div><div><br><div class="gmail_quote">2012/11/13 MORREALE Jean Roc [via OSGeo.org] <span dir="ltr"><<a href="http://user/SendEmail.jtp?type=node&node=5016218&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>></span><br>
<blockquote style="border-left:2px solid #cccccc;padding:0 1em" class="gmail_quote"><div><div class="h5"><div>
Hi,
<br><br>You could start by merging all your tiff in a VRT then do
<br>gdal_translate -of Gtiff -co SPARSE_OK=TRUE -a_nodata 0 -co NBITS=1 -co
<br>"TILED=YES" -co "COMPRESS=CCITTFAX4" -co "INTERLEAVE=BAND" "example.vrt"
<br>"example.tif"
<br><br>Le 2012-11-13 17:14, Pietro Rossin a écrit :
</div><div><br><div>> Hello all
<div><br>> I have ~1000 tiff/tfw RGB but with only 0 or 255 color value in all
<br>> bands
<br>> (black/white).
<br>> I want to mosaic them in a single image to be used in qgis and other
<br>> gis
<br>> software.
<br>>
<br>> Which is the best way to do this? And to compress the resulting
<br>> image? May
<br>> be Tiff?? Single band??
<br>> Another problem is that I must apply a formula to input images to
<br>> transform
<br>> 255 value to null, because of some white portion of each image that
<br>> overlap
<br>> to black portion of the adiacent one..
<br>>
<br>> Thanks
<br>> Pietro
</div></div></div><div>Le 2012-11-13 17:14, Pietro Rossin a écrit :
</div><div><br><div>> Hello all
<div><br>> I have ~1000 tiff/tfw RGB but with only 0 or 255 color value in all
<br>> bands
<br>> (black/white).
<br>> I want to mosaic them in a single image to be used in qgis and other
<br>> gis
<br>> software.
<br>>
<br>> Which is the best way to do this? And to compress the resulting
<br>> image? May
<br>> be Tiff?? Single band??
<br>> Another problem is that I must apply a formula to input images to
<br>> transform
<br>> 255 value to null, because of some white portion of each image that
<br>> overlap
<br>> to black portion of the adiacent one..
<br>>
<br>> Thanks
<br>> Pietro
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