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Discussion: SID - TIF

in: Orienteering; General

Oct 12, 2017 7:19 PM # 
robplow:
I have some orthophotos in SID format. Anyone know how to convert them to TIF so I can open them in OCAD? I have tried QGIS but just get errors.
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Oct 12, 2017 7:25 PM # 
Jagge:
Try irfanview, it has SID plugin.
Oct 12, 2017 7:43 PM # 
edwarddes:
QGIS will read MrSID if you have the correct plugins for it.
Oct 12, 2017 8:07 PM # 
eddie:
I've used Lizardtech's free GeoViewer in a pinch. Been a while, but it was open one file at a time, then do an "export-as." They also have a free ExpressViewer web browser plugin that can export. manual (pdf)
Oct 13, 2017 7:58 AM # 
Terje Mathisen:
The huge benefit of @Jagge's suggestion, i.e. IrfanView (which I have used for well over a decade) is that it has a batch processing feature.

In the current case it means that you can hit 'B' for batch, then select all the .sid images and enter the relevant processing options (output as JPEG? target directory? image renaming? change size/crop? etc) and then you just hit Go and it will do everything with no user intervention needed.
Oct 13, 2017 8:33 AM # 
Jagge:
It can also be used from command line i.e.you can script it (automate your typical tasks behind one double click).
Oct 13, 2017 3:55 PM # 
cedarcreek:
In QGIS, try loading them as raster layers. The newer installs might work without added plug-ins. If they won't load (as edwarddes implies), get the right plug-in.

Then in the menus at the top, use "Raster -- something -- Convert", and work through the dialog box to change them to GeoTIFF (TIF) format. Many of the boxes do not need to be filled in.

You can also use Raster -- Misc? -- Clipper to clip them to your area of interest.

Normally, I get tiles in feet (which I assume you don't have to worry about), so my workflow for small projects (i.e., I don't need tiled images) is:

Raster -- ??? --- Merge -- create one big image in TIF format
Raster -- Projections? -- reproject into UTM (changes to meters)
Raster -- Misc? -- Clipper to clip to my lidar rectangle by typing coordinates, or just draw a rectangle with your mouse.

QGIS acts as a front end for GDAL, so it removes most of the command line "what to do" issues. The dialog box generates the command line.

I only edit the command line (typically) to fix the four-band aerials to save them as three-band RGB. (I add "-b 1 -b 2 -b 3" to the end of the clipping command line, or -b 4 to save it as a pure IR image. If you want NVDI, be sure to save a clipped version of the aerial as four-band.)
Oct 13, 2017 4:04 PM # 
cedarcreek:
Also, in OOMapper, it used to be you **had to have** a world file for aerials, even TIFs. Create that in QGIS with "Raster -- something?? -- Extract Projection", then click the box for world file. It puts them out as wld files, and I rename them to extension:

tfw for TIF
jgw for jpeg
pgw for PNG

I do it with DOS: rename *.wld *.tfw
Oct 17, 2017 10:20 PM # 
robplow:
Thanks for all the suggestions.

I had already tried QGIS - I could open the SID files but the raster-convert thing just gave me error messages. A common experience when I try using QGIS .

Irfanview worked but lost the georeferencing. Geoviewer did the trick.

Cedarcreek - thanks for the detailed instructions - unfortunately 90% of them went straight over my head - any mention of ’command line' and I'm out of my league.

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