| Exporting rasters from ArcMap 9.1 to ENVI 4.0 [message #56195] |
Tue, 16 October 2007 05:39  |
Nuno Vilaça
Messages: 10
Registered: October 2007
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Junior Member |
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dear all,
i need to export some raster datasets from arcmap 9.1 to envi 4.0. i
do this by exporting the raser datasets into a tiff format so that
this can be later read by envi.
when i open these tiff images in envi, there is simply a white
background and no data is visible, just plain white. i tried arcmap
9.2 and the results are the same...
can it be a prob with my data??? anyway, i'm just converting a raster
to a tiff, no big deal... my raster is no a perfect square, but it has
some "less ortodox" borders which are visible in envi, but everything
inside the boarders is white, while the outside is black...
anyone with the same prob or with an explanation for this???
i start wondering if it is not a data prob, but my data works
perfectly on arcmap...
cheers!!!
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| Re: Exporting rasters from ArcMap 9.1 to ENVI 4.0 [message #56352 is a reply to message #56195] |
Thu, 18 October 2007 08:47  |
Jean H.
Messages: 472
Registered: July 2006
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Senior Member |
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Nuno Vila�a wrote:
> On Oct 16, 6:38 pm, Jean H <jghas...@DELTHIS.ucalgary.ANDTHIS.ca>
> wrote:
>> Nuno Vila�a wrote:
>>> dear all,
>>> i need to export some raster datasets from arcmap 9.1 to envi 4.0. i
>>> do this by exporting the raser datasets into a tiff format so that
>>> this can be later read by envi.
>>> when i open these tiff images in envi, there is simply a white
>>> background and no data is visible, just plain white. i tried arcmap
>>> 9.2 and the results are the same...
>>> can it be a prob with my data??? anyway, i'm just converting a raster
>>> to a tiff, no big deal... my raster is no a perfect square, but it has
>>> some "less ortodox" borders which are visible in envi, but everything
>>> inside the boarders is white, while the outside is black...
>>> anyone with the same prob or with an explanation for this???
>>> i start wondering if it is not a data prob, but my data works
>>> perfectly on arcmap...
>>> cheers!!!
>> Nuno,
>> When you export your data, make sure the data type is set properly...
>> and it should be the same when you open it in Envi (if I remember well,
>> it asks you for this type of info, the first time you open the image in
>> Envi).
>>
>> Jean- Hide quoted text -
>>
>> - Show quoted text -
>
> hello Jean!
>
> i export my masp as tiff images, and envi recognizes them as being
> tiff, but all tha data appears on white... i did another way of
> calculating those rasters just in case my method had an influence, but
> nthg works...
> and Jean, envi only asks for the coordinate system, and well even if
> don't input a correct one he'll always display the image, but not in
> this case... it's very strange and i haven't been able to solve this
> problem... do you have any idea of what it can be?
> thank you for your answer!
> cheers!
>
> nuno
Check the data type (not the format)... is your image a byte? a float
etc. Make sure that the data type you use when you export your image is
one that can be read by Envi... and make sure Envi knows it!
Jean
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| Re: Exporting rasters from ArcMap 9.1 to ENVI 4.0 [message #56399 is a reply to message #56195] |
Tue, 23 October 2007 09:25 |
Jean H.
Messages: 472
Registered: July 2006
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Senior Member |
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> Jean,
>
> i discovered that if i multiply my images for 100 that envi displays
> them correctly... quite strange... between 0 and 1 he does not display
> them, but between 0 and 100 he does... very weird...
Hi,
then it is just a visualization problem... if you have 255 levels of
grey and ALL your values are between 0 and 1, you will not see much...
so just apply a stretching algorithm when you display it, or define some
color for each class, depending on your data.
ArcGis, by default, stretch your data when you display it (that's why,
if you display 2 DEM, they won't have the same color for the same
elevation value...). Envi does not by default, and it is up to you to do it.
Of course, this is valid only if you expected to have these values
between 0 and 1, otherwise it is another problem!
Jean
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| Re: Exporting rasters from ArcMap 9.1 to ENVI 4.0 [message #56486 is a reply to message #56399] |
Fri, 26 October 2007 03:32 |
Nuno Vilaça
Messages: 10
Registered: October 2007
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Junior Member |
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On Oct 23, 6:25 pm, Jean H <jghas...@DELTHIS.ucalgary.ANDTHIS.ca>
wrote:
>> Jean,
>
>> i discovered that if i multiply my images for 100 that envi displays
>> them correctly... quite strange... between 0 and 1 he does not display
>> them, but between 0 and 100 he does... very weird...
>
> Hi,
>
> then it is just a visualization problem... if you have 255 levels of
> grey and ALL your values are between 0 and 1, you will not see much...
> so just apply a stretching algorithm when you display it, or define some
> color for each class, depending on your data.
>
> ArcGis, by default, stretch your data when you display it (that's why,
> if you display 2 DEM, they won't have the same color for the same
> elevation value...). Envi does not by default, and it is up to you to do it.
>
> Of course, this is valid only if you expected to have these values
> between 0 and 1, otherwise it is another problem!
>
> Jean
hi Jean!
i managed to solve the prob!
with band math, i multiply my image for 100 and then i can see
everything as i told you. still, when exporting for the software where
i want to use the images it doesn't work. with these images multiplied
by 100, i use the stretch data tool, i stretch the image from 0 to 200
and save it as a byte and then it works, pretty weird ah???
anyway thankl you for your help!
cheers!
nuno
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