Re: Pixelated, Regional Topograpy Data

The new SRTM v.3 has merged ASTER to fill voids. SRTM is better in almost e=
very location outside of voids.=20

++Eric

Sent from my iPhone

> 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 i=
s, as I recall, the highest generally available resolution, however it is n=
oisy; e.g.; a tile near the Galapagos has a few points indicating ~7,000m e=
levation on Isla Darwin.
>=20
> We take all the land data we can get easily and block median it together =
for that reason. Simply taking an average would not work well. And the GMT =
tools are fast so the extra computer time is negligible=85
>=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=92d like to 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 m=
edian height from a cloud of neighboring points (aka the center of the down=
 sampled pixel, the average location of the cloud, the location whose heigh=
t happens to be the median, etc=85)
>=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 =
would be the best way to convert the .hgt files (I have 4 that I want to co=
nvert) into .grd files, then stich those files together?  Could I use xyz2g=
rd and 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_sta=
tes_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
>> =B3pscoast=B2 is defaulting to a low resolution coastline. Try adding -D=
f or
>> check the usage message to get your highest option.
>>=20
>> There is higher resolution topography than ETOPO1, such as SRTM3. You=B9=
ll
>> 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
>>> have found a bug, discuss it here first. To formally report bugs or
>>> request features, please register and add New Issue on
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t-help will become obsolete on Sept
>>> 1, 2014 - please use forum on gmt.soest.hawaii.edu<http://gmt.soest.haw=
aii.edu/> instead.
>>=20
>> 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
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n
>> 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 h=
ave 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<http://gmt.soest.hawaii.edu/>
> To unsubscribe, send the message "signoff gmt-help" to [email protected]=
aii.edu<mailto:[email protected]>
> Note: gmt-help will become obsolete on Sept 1, 2014 - please use forum on=
 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 f=
eatures, please register and add New Issue on gmt.soest.hawaii.edu<http://g=
mt.soest.hawaii.edu/> To unsubscribe, send the message "signoff gmt-help" t=
o [email protected]<mailto:[email protected]> Note: gmt-hel=
p will become obsolete on Sept 1, 2014 - please use forum on gmt.soest.hawa=
ii.edu<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 =
Issue on gmt.soest.hawaii.edu
> To unsubscribe, send the message "signoff gmt-help" to [email protected]=
aii.edu
> Note: gmt-help will become obsolete on Sept 1, 2014 - please use forum on=
 gmt.soest.hawaii.edu instead.

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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.