Re: [PROJ] LIBERTIFF / Thread-safe TIFF reader

Howard Butler via gdal-dev <[email protected]> Sun, 22 Dec 2024 08:38:52 -0600
Newsgroups gmane.comp.gis.gdal.devel,gmane.comp.gis.proj-4.devel
Message-ID <[email protected]>
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> On Dec 20, 2024, at 4:56=E2=80=AFPM, Even Rouault via gdal-dev =
<[email protected]> wrote:
>=20
> Besides reprocessing all of our existing =
grids,https://github.com/geotiffjs/geotiff.js/tree/master/src/compression =
seems to show that it doesn't support ZSTD, which would break at least =
our wonderful cdn.proj.org <http://cdn.proj.org/>interactive map

To throw a wrench into it...=20

geotiff.js has LERC support. Floating point LERC TIFFs compressed with a =
MAX_Z_ERROR to one decimal better than the *stated precision* of the =
grids would be smaller and more efficiently compressed/decompressed. By =
maybe a 1/3rd over zstd and deflate.

See this great write-up by LINZ about the topic =
https://github.com/linz/elevation/tree/master/docs/tiff-compression=20

Howard=

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"overflow-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;"><br =
id=3D"lineBreakAtBeginningOfMessage"><div><br><blockquote =
type=3D"cite"><div>On Dec 20, 2024, at 4:56=E2=80=AFPM, Even Rouault via =
gdal-dev &lt;[email protected]&gt; wrote:</div><br =
class=3D"Apple-interchange-newline"><div><meta charset=3D"UTF-8"><span =
style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: =
18px; font-style: normal; font-variant-caps: normal; font-weight: 400; =
letter-spacing: normal; text-align: start; text-indent: 0px; =
text-transform: none; white-space: normal; word-spacing: 0px; =
-webkit-text-stroke-width: 0px; text-decoration: none; float: none; =
display: inline !important;">Besides reprocessing all of our existing =
grids,</span><a class=3D"moz-txt-link-freetext" =
href=3D"https://github.com/geotiffjs/geotiff.js/tree/master/src/compressio=
n" style=3D"font-family: Helvetica; font-size: 18px; font-style: normal; =
font-variant-caps: normal; font-weight: 400; letter-spacing: normal; =
orphans: auto; text-align: start; text-indent: 0px; text-transform: =
none; white-space: normal; widows: auto; word-spacing: 0px; =
-webkit-text-stroke-width: =
0px;">https://github.com/geotiffjs/geotiff.js/tree/master/src/compression<=
/a><span style=3D"caret-color: rgb(0, 0, 0); font-family: Helvetica; =
font-size: 18px; font-style: normal; font-variant-caps: normal; =
font-weight: 400; letter-spacing: normal; text-align: start; =
text-indent: 0px; text-transform: none; white-space: normal; =
word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: =
none; float: none; display: inline !important;"><span =
class=3D"Apple-converted-space">&nbsp;</span>seems to show that it =
doesn't support ZSTD, which would break at least our wonderful<span =
class=3D"Apple-converted-space">&nbsp;</span></span><a =
href=3D"http://cdn.proj.org/" style=3D"font-family: Helvetica; =
font-size: 18px; font-style: normal; font-variant-caps: normal; =
font-weight: 400; letter-spacing: normal; orphans: auto; text-align: =
start; text-indent: 0px; text-transform: none; white-space: normal; =
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: =
0px;">cdn.proj.org</a><span style=3D"caret-color: rgb(0, 0, 0); =
font-family: Helvetica; font-size: 18px; font-style: normal; =
font-variant-caps: normal; font-weight: 400; letter-spacing: normal; =
text-align: start; text-indent: 0px; text-transform: none; white-space: =
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
text-decoration: none; float: none; display: inline =
!important;">interactive map</span></div></blockquote></div><br><div>To =
throw a wrench into it...&nbsp;</div><div><br></div><div>geotiff.js has =
LERC support. Floating point LERC TIFFs compressed with a MAX_Z_ERROR to =
one decimal better than the *stated precision* of the grids would be =
smaller and more efficiently compressed/decompressed. By maybe a 1/3rd =
over zstd and deflate.</div><div><br></div><div>See this great write-up =
by LINZ about the =
topic&nbsp;https://github.com/linz/elevation/tree/master/docs/tiff-compres=
sion&nbsp;</div><div><br></div><div>Howard</div></body></html>=

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