[gdal-dev] Converting .NET Bitmap to GDAL Dataset

Sun Mar 24 06:23:49 PDT 2013

This is because there's no driver to recognise the image data directly. You
should provide the image file in a GDAL supported binary format (like jpg
or png or tif) or use the MEM driver to represent the dataset. I've created
a new sample for this approach at:

http://trac.osgeo.org/gdal/browser/trunk/gdal/swig/csharp/apps/GDALMemDataset.cs

In this example I create the bands in a reverse order as it looks like the
Windows bitmap format requires it.

Best regards,

Tamas

2013/3/23 Maksim Sestic <max at geoinova.com>

>  It's a Bitmap instance created using:****
>
> ** **
>
> Dim bmp As Bitmap = Bitmap.FromFile("C:\Input.png")****
>
> ** **
>
> then converted to byte array (as per MSDN article):****
>
> ** **
>
> ' Lock the bitmap's bits.****
>
> Dim rect As New Rectangle(0, 0, bmp.Width, bmp.Height)****
>
> Dim bmpData As BitmapData = bmp.LockBits(rect, ImageLockMode.ReadOnly,
> bmp.PixelFormat)****
>
> ** **
>
> ' Get the address of the first line.****
>
> Dim ptr As IntPtr = bmpData.Scan0****
>
> ** **
>
> ' Declare an array to hold the bytes of the bitmap.****
>
> Dim bitmapData As Byte()****
>
> ReDim bitmapData(Math.Abs(bmpData.Stride) * bmp.Height)****
>
> ** **
>
> ' Copy the RGB values into the array.****
>
> Marshal.Copy(ptr, bitmapData, 0, bitmapData.Length)****
>
> ** **
>
> ' Unlock the bits.****
>
> bmp.UnlockBits(bmpData)****
>
> ** **
>
> The rest is your code (abbreviated version):****
>
> ** **
>
> 'Code provided by Tamas Szekeres****
>
> Gdal.AllRegister()****
>
> Dim handle As GCHandle = GCHandle.Alloc(bitmapData, GCHandleType.Pinned)**
> **
>
> Dim memFilename As String = "/vsimem/inmemfile"****
>
> Gdal.FileFromMemBuffer(memFilename, bitmapData.Length,
> handle.AddrOfPinnedObject())****
>
> Dim ds As Dataset = Gdal.Open(memFilename, Access.GA_ReadOnly)     '<<<
> Exception gets thrown at this line****
>
> Dim drv As Driver = Gdal.GetDriverByName("GTiff")****
>
> drv.CreateCopy("C:\Output.tif", ds, 0, Nothing, Nothing, Nothing)****
>
> Gdal.Unlink(memFilename)****
>
> handle.Free()****
>
> ** **
>
> Sorry about my VB.NET :-) ****
>
> ** **
>
> I'm certain it's not about assembly referencing issues and such, since it
> works correctly using "classic" Gdal.Open(...) method.****
>
> ** **
>
> Regards,****
>
> Maksim Sestic****
>
> ** **
>
> ** **
>  ------------------------------
>
> *From:* Tamas Szekeres [mailto:szekerest at gmail.com]
> *Sent:* Saturday, March 23, 2013 23:46
>
> *To:* Maksim Sestic
> *Subject:* Re: [gdal-dev] Converting .NET Bitmap to GDAL Dataset
> ****
>
>  ** **
>
> What is the input file you are using?****
>
> ** **
>
> Tamas****
>
> ** **
>
> 2013/3/23 Maksim Sestic <max at geoinova.com>****
>
> Hi Tamas,****
>
>  ****
>
> It throws exception at line:****
>
>  ****
>
> Dataset ds = Gdal.Open(memFilename, Access.GA_ReadOnly);****
>
>  ****
>
> ...saying that "/vsimem/inmemfile" is not a recognized format.****
>
>  ****
>
> I'm using GDAL 1.8.0, could it be version-related?****
>
>  ****
>
> Regards,****
>
> Maksim Sestic ****
>
>  ****
>  ------------------------------
>
> *From:* Tamas Szekeres [mailto:szekerest at gmail.com]
> *Sent:* Saturday, March 23, 2013 22:11****
>
>
> *To:* Maksim Sestic
> *Subject:* Re: [gdal-dev] Converting .NET Bitmap to GDAL Dataset****
>
>  ****
>
> Added a C# example to demonstrate the usage of the /vsimem facilities.****
>
>  ****
>
> http://trac.osgeo.org/gdal/browser/trunk/gdal/swig/csharp/apps/VSIMem.cs**
> **
>
>  ****
>
> Best regards,****
>
>  ****
>
> Tamas****
>
>  ****
>
>  ****
>
>  ****
>
> 2013/3/23 Maksim Sestic <max at geoinova.com>****
>
> Hi Tamas,****
>
>  ****
>
> Thanks for the help. I recall hitting this issue before as well:
> http://lists.osgeo.org/pipermail/gdal-dev/2012-May/032972.html****
>
>  ****
>
> Regards,****
>
> Maksim Sestic****
>
>  ****
>
> P.S.****
>
> Sorry, just noticed that the conversation went to priv. only and not to
> gdal-dev forum.****
>
>  ****
>  ------------------------------
>
> *From:* Tamas Szekeres [mailto:szekerest at gmail.com]
> *Sent:* Saturday, March 23, 2013 10:56****
>
>
> *To:* Maksim Sestic
> *Subject:* Re: [gdal-dev] Converting .NET Bitmap to GDAL Dataset****
>
>  ****
>
> You may probably utilize the MEM driver (http://www.gdal.org/frmt_mem.html)
> or the vsimem virtual file system
> http://gdal.org/cpl__vsi_8h.html#a66e2e6f093fd42f8a941b962d4c8a19e****
>
>  ****
>
> Best regards,****
>
>  ****
>
> Tamas****
>
>  ****
>
> 2013/3/22 Maksim Sestic <max at geoinova.com>****
>
> Hi Tamas,****
>
>  ****
>
> You're right, thanks. ****
>
>  ****
>
> I was trying to create a pair of "roundtrip" classes utilizing Gdal. First
> one would read e.g. a file into Bitmap instance, that's what GDALRead.cs
> demonstrates perfectly. The other would write this Bitmap instance using
> Gdal drivers back to e.g. another file. You might have guessed that I was
> stuck at the second one. I neve actually coded against Gdal memory driver,
> should give it a try I guess...****
>
>  ****
>
> Regards,****
>
> Maksim Sestic****
>
>  ****
>  ------------------------------
>
> *From:* Tamas Szekeres [mailto:szekerest at gmail.com]
> *Sent:* Friday, March 22, 2013 22:58
> *To:* Maksim Sestic
> *Subject:* Re: [gdal-dev] Converting .NET Bitmap to GDAL Dataset****
>
>  ****
>
> Dataset is considered as an interface to the underlying driver. Aside from
> the 'in memory driver' and some sort of internal caching facilities the
> dataset doesn't hold data in memory. In this regard we cannot convert these
> 2 objects types to each other. The most obvious action regarding to your
> requirement is to create and in memory dataset and copy data from the
> bitmap to the dataset, as I've mentioned before.****
>
>  ****
>
> Best regards,****
>
>  ****
>
> Tamas****
>
>  ****
>
>  ****
>
> 2013/3/22 Maksim Sestic <max at geoinova.com>****
>
> Hi Tamas,****
>
>  ****
>
> If I'm not mistaken, GDALWrite.cs and GDALDatasetWrite.cs examples are
> about writing (using Create() method) a dataset to disk. What I'm trying to
> do is to convert a System.Drawing.Bitmap instance to a GDAL.Dataset,
> in-memory only. But I'm not sure about how to do it...****
>
>  ****
>
> Regards,****
>
> Maksim Sestic****
>
>  ****
>
>  ****
>  ------------------------------
>
> *From:* gdal-dev-bounces at lists.osgeo.org [mailto:
> gdal-dev-bounces at lists.osgeo.org] *On Behalf Of *Tamas Szekeres
> *Sent:* Friday, March 22, 2013 21:12
> *To:* gdal-dev
> *Subject:* [gdal-dev] Converting .NET Bitmap to GDAL Dataset****
>
>  ****
>
>  ****
>
> For an example of the reverse action see SaveBitMapDirect in
> GDALReadDirect.cs<http://trac.osgeo.org/gdal/browser/trunk/gdal/swig/csharp/apps/GDALReadDirect.cs>
>  ****
>
> To write data to GDAL dataset see: GDALWrite.cs<http://trac.osgeo.org/gdal/browser/trunk/gdal/swig/csharp/apps/GDALWrite.cs>or
> GDALDatasetWrite.cs<http://trac.osgeo.org/gdal/browser/trunk/gdal/swig/csharp/apps/GDALDatasetWrite.cs>
> ****
>
>  ****
>
> Best regards,****
>
>  ****
>
> Tamas****
>
>  ****
>
>  ****
>
> 2013/3/22 Maksim Sestic <max at geoinova.com>****
>
> Hi all,
>
> Is there any example (or a hint) of converting a System.Drawing.Bitmap into
> GDAL Dataset?
>
> Regards,
> Maksim Sestic
>
>
>
> --
> View this message in context:
> http://osgeo-org.1560.n6.nabble.com/Converting-NET-Bitmap-to-GDAL-Dataset-tp5042430.html
> Sent from the GDAL - Dev mailing list archive at Nabble.com.
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> http://lists.osgeo.org/mailman/listinfo/gdal-dev****
>
>  ****
>
>  ****
>
>  ****
>
>  ****
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>  ****
>
> ** **
>
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