<div dir="ltr"><div><div><p><font face="arial, sans-serif">Dear Developers,</font></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">I am working on generating a mosaic, and I need to ensure that the maximum pixel value (dBZ) is selected when merging overlapping raster files. Despite my attempts using <code>gdalbuildvrt</code> and <code>gdalwarp</code>, I continue to encounter issues where it does not always pick the maximum pixel value in overlapping areas.</font></p><p><font face="arial, sans-serif">notes: CRS is <span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">EPSG:4326 and </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">GDAL 3.8.5, released 2024/04/02</span></font></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">Commands Used:</font></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">1.<br>gdalwarp -overwrite -multi -r max  /nfs/radar/max-reflectivity/tiff/raw/*/2025/3/5/20250305T2145*.tif test-20250305T2145.png.composite.tif</font></p></div><div><font face="arial, sans-serif">or </font></div><div><font face="arial, sans-serif">gdalbuildvrt test-20250305T2145.png.composite.vrt /nfs/radar/max-reflectivity/tiff/raw/*/2025/3/5/20250305T2145*.tif </font></div><div><font face="arial, sans-serif"><br></font></div><div><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">gdalwarp -overwrite -q -r max test-20250305T2145.png.composite.vrt test-20250305T2145.png.composite.tif</font></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif"><br></font></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">2.</font></p><p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-variant-alternates:normal;font-size-adjust:none;font-kerning:auto;font-feature-settings:normal;font-stretch:normal;line-height:normal"><font face="arial, sans-serif">gdaldem color-relief -alpha -q test-20250305T2145.composite.tif \ /color-ramps/reflectivity/titan.txt \ test-20250305T2145.png<br></font></p></div><div><h3><strong><font size="2" face="arial, sans-serif">Questions:</font></strong></h3><ol><li style="margin-left:15px"><font face="arial, sans-serif">How can I ensure that gdalbuildvrt properly stacks overlapping rasters while keeping the maximum pixel values?</font></li><li style="margin-left:15px"><font face="arial, sans-serif">Is gdalwarp -r max the correct approach to pick the highest dBZ reflectivity values?</font></li></ol><p><font face="arial, sans-serif">Any guidance or suggestions would be greatly appreciated! Thank you in advance for your help.</font></p><p><span style="font-family:arial,sans-serif">With Regards,</span></p></div></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><img src="https://ci3.googleusercontent.com/mail-sig/AIorK4xXK2FcuLB-McWvVDY_UHTgn0ECtSzGSI2UMpZ6UOXD6f7owItf-zS-kvkRhXhBZnW4eOSsuvM" width="96" height="28"><br></div></div></div>