How to merge raster files in ArcGIS?

[HaoHuang]

I tried merge function from Map algebra in the Spatial Analysis Toolbox, but doesn't work. who kow how to deal with it? Thanks a lot....

[CrystalDorn]

Without more details or a description of the error you received it's not possible to comment, for example, I assume you are using the Single Output Map Algebra tool? 

In the meantime, start with:
Your Toolbox ENVIRONMENT settings, e.g. input projections and processing output projections, path to output workspace?, etc.

Have you tried to use the Mosaic to New Raster tool?

[JakubSisak]

ArcToolbox -> Data Management Tools -> Raster -> Raster Dataset -> Mosaic To New Raster

[AsparuhKamburov]

ArcToolbox -> Data Management Tools -> Raster -> Raster Dataset -> Mosaic To New Raster

Yep, that works fine. Thanks a lot!

[ToddMacPherson]

Thanks for this. An oldie but a goodie.

[curtvprice]

The real oldie and goody is merge(), which with "real" Con was removed at 10.0. (Though the rough edges of the Mosaic tool have been smoothed a bit (haha).  Mosaic, being a core raster tool, is not integrated in arcpy map algebra, which is a pity.

More map-algebra friendly replacements for the old (missing) merge function include:

- CellStatistics with the "DATA" parameter, using an appropriate statistics choice in case there is overlap (For example - "MAXIMUM" or "MEAN")

CellStatistics([raster1, raster2, raster3], "MEAN", "NODATA")

- Use Con and IsNull to get the first in the list that is non-NoData

Con(^ IsNull(raster1), raster1, Con(^ IsNull(raster2), raster2)))
Con(^ IsNull(raster1), raster1, Con(^ IsNull(raster2), raster2, Con(^ IsNull(raster3), raster3)))

- You can still use SOMA (this is only supported for backwards compatibility).

expr = "merge({0}".format(",".join[str(r) for r in [raster1, raster2, raster3]])
tmpras  = arcpy.CreateScratchName("","","raster")
outras = Raster(arcpy.gp.SingleOutputMapAlgebra_sa(expr,  tmpras))

Please join me and vote this up!

ideas.arcgis.com: Bring back Spatial Analyst Merge tool

UPDATE: I have posted an arcpy map algebra implementation of the old merge() functionality.

Implementing merge() in ArcPy map algebra​

[StephenJordan2]

Hey Guys, thanks for all your help I actually used the Extract by Attributes tool SQL query Where "Rowid" =1 in the end.

all done and looking good now