Re: Pixelated, Regional Topograpy Data

> On 11/08/2014, at 09:23, "Fielding, Eric J (329A)" <[email protected]=
SA.GOV> wrote:
>=20
> The new SRTM v.3 has merged ASTER to fill voids. SRTM is better in almost e=
very location outside of voids.=20

And it takes 9 times less disk space

Joaquim


Sent from my iPadiola

>=20
> ++Eric
>=20
> Sent from my iPhone
>=20
>> On Aug 11, 2014, at 12:17, "Becker, Joseph J." <Joseph.Becker.ctr@NRLSSC.=
NAVY.MIL> wrote:
>>=20
>> I forgot to mention that we now combine the SRTM land data with the ASTER=
 data which is also available for free. Outside of the US, the ASTER data is=
, as I recall, the highest generally available resolution, however it is noi=
sy; e.g.; a tile near the Galapagos has a few points indicating ~7,000m elev=
ation on Isla Darwin.
>>=20
>> We take all the land data we can get easily and block median it together f=
or that reason. Simply taking an average would not work well. And the GMT to=
ols are fast so the extra computer time is negligible=E2=80=A6
>>=20
>> -jj
>>=20
>>=20
>> On Aug 11, 2014, at 10:38 AM, JJ Becker <[email protected]=
l<mailto:[email protected]>> wrote:
>>=20
>> I make the SRTM30_PLUS file(s) that were mention. If you=E2=80=99d like t=
o make your own at a higher resolution here is what I do:
>>=20
>> a bit of byte swapping on the HGT format file(s),
>> (optionally cat several altogether in a tmp file),
>> (optionally) block median the small tiles together to get the final resol=
ution you would like,
>> and grid.
>>=20
>>=20
>> grd2xyz $cgiar -s -bo3 -V |
>> blockmedian -bi3 -bo3 -I$resolution -R$minX/$maxX/$minY/$maxY -C -V | \
>> xyz2grd -bi -G$grd  -R$minX/$maxX/$minY/$maxY -I$resolution -V
>>=20
>>=20
>> The block median options can be used to handle the possibly troubling iss=
ues arising from the question of what location to pick when selecting the me=
dian height from a cloud of neighboring points (aka the center of the down s=
ampled pixel, the average location of the cloud, the location whose height h=
appens to be the median, etc=E2=80=A6)
>>=20
>> -jj
>>=20
>> On Aug 9, 2014, at 3:13 PM, Gregory (Greg) Brenn <[email protected]<=
mailto:[email protected]>> wrote:
>>=20
>> Ok,
>>=20
>> That's great.  I downloaded an unzipped .hgt files, so what do you think w=
ould be the best way to convert the .hgt files (I have 4 that I want to conv=
ert) into .grd files, then stich those files together?  Could I use xyz2grd a=
nd then use grdpaste?
>>=20
>> Thanks a lot for your help.
>> Greg
>>=20
>>=20
>> On Sat, Aug 9, 2014 at 2:44 PM, Fielding, Eric J (329A) <eric.j.fielding@=
jpl.nasa.gov<mailto:[email protected]>> wrote:
>> Yes, as Walter mentioned, the SRTM 3-arcsecond (~90 m) digital topography=

>> is available for most of the Earth (up to 60 degrees N & S latitudes), an=
d
>> it is much higher resolution than the ETOPO1 data that is 1-arcminute or
>> about 2 km spacing. The latest release is SRTM version 3.0. The Open
>> Topography website has a new service that will assemble the data and
>> provide the output in three formats
>> (http://www.opentopography.org/index.php/news/detail/srtm_version_30_glob=
al
>> _90m_and_united_states_30m_elevation_data_now_availab/<http://www.opentop=
ography.org/index.php/news/detail/srtm_version_30_global_90m_and_united_stat=
es_30m_elevation_data_now_availab/>). The GeoTIFF files
>> are easy to convert to GMT .grd files with GDAL.
>>=20
>> ++Eric Fielding
>>=20
>>=20
>> -----Original Message-----
>> From: "Walter  Smith  (HF)" <[email protected]<mailto:walter.hf.sm=
[email protected]>>
>> Reply-To: World-Wide GMT Usage and Help Mailing List
>> <[email protected]<mailto:[email protected]>>
>> Date: Saturday, August 9, 2014 11:04 AM
>> To: "[email protected]<mailto:[email protected]>" <GMT-HE=
[email protected]<mailto:[email protected]>>
>> Subject: Re: [GMT-HELP] Pixelated, Regional Topograpy Data
>>=20
>>> =C2=B3pscoast=C2=B2 is defaulting to a low resolution coastline. Try add=
ing -Df or
>>> check the usage message to get your highest option.
>>>=20
>>> There is higher resolution topography than ETOPO1, such as SRTM3. You=C2=
=B9ll
>>> have to search around and you may have to assemble it from a few tiles
>>> that you may have to download separately.
>>>=20
>>> Walter
>>>=20
>>> On Aug 9, 2014, at 1:50 PM, Gregory (Greg) Brenn <[email protected]=
<mailto:[email protected]>>
>>> wrote:
>>>=20
>>>> Hello,
>>>>=20
>>>> New user of GMT here, and I'm attempting to create a map of Costa Rica
>>>> and overlay coastlines and earthquake locations.  Here is my Script:
>>>>=20
>>>> #!/bin/bash
>>>>=20
>>>> clear
>>>>=20
>>>> xyz2grd COSTARIC-6565.xyz -Gcostarica.grd -R-87/-84/9/11 -I2m -V
>>>>=20
>>>> grdimage costarica.grd -JM12 -K -Cmy-topo.cpt -R-87/-84/9/11 >> map.ps<=
http://map.ps/>
>>>>=20
>>>> pscoast -V -O -K -JM -R -W1 >> mappy.ps<http://mappy.ps/>
>>>>=20
>>>> psxy loc.txt -JM12 -R-87/-84/9/11 -Sc.1 -G'45/59/100' -B1/1 -O >> map.p=
s<http://map.ps/>
>>>> gv map.ps<http://map.ps/>
>>>>=20
>>>>=20
>>>>=20
>>>> I am using a generic color palette which I can change easily, but the
>>>> coastlines are extremely low quality, and the topography is extremely
>>>> pixelated.
>>>>=20
>>>> I look at images in papers, and there's extremely high quality
>>>> topographic images of COsta Rica, for example, as well as the coastline=
s
>>>> and bathymetry, but I have no idea where I can get this high-quality
>>>> data.  I have tried to get ETOPO data, but I cannot seem to find where
>>>> to get high-quality data.
>>>>=20
>>>> So I guess my question is, is ETOPO1 the best place to get high-quality=

>>>> topo data, because I cannot seem to figure out how to download data fro=
m
>>>> their website.  Also, would I need to download coastline data, as well?=

>>>>=20
>>>>=20
>>>>=20
>>>> Thanks,
>>>>=20
>>>> Greg
>>>>=20
>>>> Mailing list for GMT discussions of all kinds. If you are not sure you
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aii.edu/> instead.
>>>=20
>>> Mailing list for GMT discussions of all kinds.  If you are not sure you
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>>=20
>> Mailing list for GMT discussions of all kinds.  If you are not sure you h=
ave found a bug, discuss it here first.
>> To formally report bugs or request features, please register and add New I=
ssue on gmt.soest.hawaii.edu<http://gmt.soest.hawaii.edu/>
>> To unsubscribe, send the message "signoff gmt-help" to [email protected]=
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 gmt.soest.hawaii.edu<http://gmt.soest.hawaii.edu/> instead.
>>=20
>> Mailing list for GMT discussions of all kinds. If you are not sure you ha=
ve found a bug, discuss it here first. To formally report bugs or request fe=
atures, please register and add New Issue on gmt.soest.hawaii.edu<http://gmt=
.soest.hawaii.edu/> To unsubscribe, send the message "signoff gmt-help" to l=
[email protected]<mailto:[email protected]> Note: gmt-help wi=
ll become obsolete on Sept 1, 2014 - please use forum on gmt.soest.hawaii.ed=
u<http://gmt.soest.hawaii.edu/> instead.
>>=20
>> Mailing list for GMT discussions of all kinds.  If you are not sure you h=
ave found a bug, discuss it here first.
>> To formally report bugs or request features, please register and add New I=
ssue on gmt.soest.hawaii.edu
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>> Note: gmt-help will become obsolete on Sept 1, 2014 - please use forum on=
 gmt.soest.hawaii.edu instead.
>=20
> Mailing list for GMT discussions of all kinds.  If you are not sure you ha=
ve found a bug, discuss it here first.
> To formally report bugs or request features, please register and add New I=
ssue on gmt.soest.hawaii.edu
> To unsubscribe, send the message "signoff gmt-help" to [email protected]=
ii.edu
> Note: gmt-help will become obsolete on Sept 1, 2014 - please use forum on g=
mt.soest.hawaii.edu instead.

Mailing list for GMT discussions of all kinds.  If you are not sure you have found a bug, discuss it here first.
To formally report bugs or request features, please register and add New Issue on gmt.soest.hawaii.edu
To unsubscribe, send the message "signoff gmt-help" to [email protected]
Note: gmt-help will become obsolete on Sept 1, 2014 - please use forum on gmt.soest.hawaii.edu instead.