<div dir="ltr">Thanks for an admirably complete question, with sufficient information<div>to meaningfully attempt to answer it.<div><br></div><div>Unfortunately, my answer will probably disappoint you.</div><div><br></div><div>After 7 iterations your deviation from the origin is less than a micrometre</div><div>in X and less than one tenth of a millimetre in Y.</div></div><div><br></div><div>Since PROJ.4 uses numerical, not analytical, mathematics, and since the</div><div>resolution is limited by the mantissa size of IEEE-754 64 bit doubles, the</div><div>roundtrips will never (for a rather all-encompassing value of never) be exact.</div><div>Typically, they will converge after a few hundred iterations, after which the</div><div>deviation will cease to grow overall, but they will still not be exact.</div><div><br></div><div>To me, it is slightly surprising that you get exact roundtrips for mercator,</div><div>although the ellipsoidal mercator projection is somewhat simpler than</div><div>ellipsoidal LCC, so it will probably be more probable.</div><div><br></div><div>So my overall message is that you should not expect exact roundtrips.</div><div>Another thing is that it surprises me you need exact roundtrips after</div><div>an operation that involves direct user interaction. Which human</div><div>interaction is it that touches up data at the micrometer level, and needs</div><div>exact replication? If you could tell a bit about this it might be easier to</div><div>see potential workarounds.</div><div><br></div><div><br></div><div><br></div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">2017-10-31 7:50 GMT+01:00 Dmitry Mefed <span dir="ltr"><<a href="mailto:dmitrymefed@gmail.com" target="_blank">dmitrymefed@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><p class="MsoNormal"><span lang="EN-US">Hi,</span></p><p class="MsoNormal"><span lang="EN-US"><br></span></p>
<p class="MsoNormal"><span lang="EN-US">Our
software stores the data with EPSG 4269 and present to the User in a local
projected CRS, EPSG 2285 in examples described below. In case if an entity is
modified on the UI we need to push the changes back. In that scenario we have
to do </span></p>
<p class="m_7597960368558449909gmail-m_-5491966359676502627gmail-MsoListParagraphCxSpFirst"><span lang="EN-US"><span>1.<span style="font:7pt "Times New Roman""> </span></span></span><span lang="EN-US">4269 -> 2285 projection, </span></p>
<p class="m_7597960368558449909gmail-m_-5491966359676502627gmail-MsoListParagraphCxSpMiddle"><span lang="EN-US"><span>2.<span style="font:7pt "Times New Roman""> </span></span></span><span lang="EN-US">then User modifies the entity (in
2285 CRS), </span></p>
<p class="m_7597960368558449909gmail-m_-5491966359676502627gmail-MsoListParagraphCxSpMiddle"><span lang="EN-US"><span>3.<span style="font:7pt "Times New Roman""> </span></span></span><span lang="EN-US">In order to store the changes, we do
2285 -> 4269 projection </span></p>
<p class="m_7597960368558449909gmail-m_-5491966359676502627gmail-MsoListParagraphCxSpLast"><span lang="EN-US"><span>4.<span style="font:7pt "Times New Roman""> </span></span></span><span lang="EN-US">and next time the entity is
requested we do 4269 -> 2285 projection again.</span></p>
<p class="MsoNormal"><span lang="EN-US">The problem
is that proj4 does not produce same results in step 2 and 4. It would be
expected behavior as 2285 provides more precision due to used units US-ft, in
comparison to 4269 which units are degrees. But the real issue for us is that
subsequent transformations between 2285 -> 4269 -> 2285… produces growing
error. Please consider the following output of cs2cs program, (in parallel I
did inverse projection to obtain coordinates in EPSG 4269):</span></p>
<p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">C:\PROJ\bin>cs2cs.exe
-v +init=epsg:2285 +to +init=epsg:4269 -f %.16f</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">pj_open_lib(epsg):
call fopen(C:\proj\share\epsg) - succeeded</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace"> </span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">pj_open_lib(epsg):
call fopen(C:\proj\share\epsg) - succeeded</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace"> </span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
---- From Coordinate System ----</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#Lambert
Conformal Conic</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#<span> </span>Conic, Sph&Ell</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#<span> </span>lat_1= and lat_2= or lat_0</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
+init=epsg:2285 +proj=lcc +lat_1=48.73333333333333 +lat_2=47.5 +lat_0=47</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
+lon_0=-120.8333333333333 +x_0=500000.0001016001 +y_0=0 +datum=NAD83</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
+units=us-ft +no_defs +ellps=GRS80 +towgs84=0,0,0</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
---- To Coordinate System ----</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#Lat/long
(Geodetic alias)</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
+init=epsg:4269 +proj=longlat +datum=NAD83 +no_defs +ellps=GRS80</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">#
+towgs84=0,0,0</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.<a href="tel:(318)%20406-6000" value="+13184066000" target="_blank">3184066000</a>
643350.39301622100</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999860520 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184067495000000<span> <wbr> </span>643350.3930111383100000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999721180 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184069018000000<span> <wbr> </span>643350.3930060574800000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999581850 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184070541000000<span> <wbr> </span>643350.3930009742000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999442440 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184072063000000<span> <wbr> </span>643350.3929958911600000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999302960 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184073586000000<span> <wbr> </span>643350.3929908055600000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999163550 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184075109000000<span> <wbr> </span>643350.3929857177400000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309999023930 0.0000000000000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">2196293.3184076636000000<span> <wbr> </span>643350.3929806276000000</span></font></p><font size="1"><span style="font-family:monospace,monospace">
</span></font><p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><font size="1"><span style="font-family:monospace,monospace">-118.5293900000000300<span> </span>48.7408309998884450 0.0000000000000000</span></font></p>
<p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><span style="font-family:Consolas" lang="EN-US"> </span></p>
<p class="MsoNormal"><b><span lang="EN-US">Simple Excel based analysis shows the following
deltas on each step:</span></b></p>
<table style="width:332.9pt;border-collapse:collapse" class="m_7597960368558449909gmail-m_-5491966359676502627gmail-MsoNormalTable" border="0" cellpadding="0" cellspacing="0" width="444">
<tbody><tr style="height:14.4pt">
<td style="width:80.45pt;border-width:1pt;border-style:solid;border-color:windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">X</span></p>
</td>
<td style="width:80.45pt;border-width:1pt 1pt 1pt medium;border-style:solid solid solid none;border-color:windowtext windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">dX</span></p>
</td>
<td style="width:80.45pt;border-width:1pt 1pt 1pt medium;border-style:solid solid solid none;border-color:windowtext windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">Y</span></p>
</td>
<td style="width:91.55pt;border-width:1pt 1pt 1pt medium;border-style:solid solid solid none;border-color:windowtext windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">dY</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840660000</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US"> </span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39301622100</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US"> </span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840674950</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000014950</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39301113831</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000508269</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840690180</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000015230</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39300605748</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000508083</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840705410</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000015230</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39300097420</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000508328</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840720630</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000015220</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39299589116</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000508304</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840735860</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000015230</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39299080556</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000508560</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840751090</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000015230</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39298571774</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000508782</span></p>
</td>
</tr>
<tr style="height:14.4pt">
<td style="width:80.45pt;border-width:medium 1pt 1pt;border-style:none solid solid;border-color:-moz-use-text-color windowtext windowtext;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,31840766360</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,00000015270</span></p>
</td>
<td style="width:80.45pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="107">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">0,39298062760</span></p>
</td>
<td style="width:91.55pt;border-width:medium 1pt 1pt medium;border-style:none solid solid none;border-color:-moz-use-text-color windowtext windowtext -moz-use-text-color;padding:0cm 5.4pt;height:14.4pt" nowrap valign="bottom" width="122">
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-0,00000509014</span></p>
</td>
</tr>
</tbody></table>
<p style="margin-bottom:0.0001pt;line-height:normal" class="MsoNormal"><span style="font-family:Consolas" lang="EN-US"> </span></p>
<p class="MsoNormal"><span lang="EN-US">I also
tried other LCC CRSs the picture is similar. And I also tried Mercator projection
EPSG 3857 it does not seem to have such issue, after full cycle of projections,
it produces constant results in both directions.</span></p>
<p class="MsoNormal"><span lang="EN-US">Please let
me know if it is known issue or it is WAD (Works As Designed) or if I can do
something with this.</span></p><p class="MsoNormal"><span lang="EN-US"><br></span></p><p class="MsoNormal"><span lang="EN-US">PS</span></p><p class="MsoNormal"><span lang="EN-US">this is the second window output:</span></p><p class="MsoNormal"><span lang="EN-US"><font size="1"><span style="font-family:monospace,monospace">C:\PROJ\bin>cs2cs.exe -v +init=epsg:4269 +to +init=epsg:2285 -f %.16f<br># ---- From Coordinate System ----<br>#Lat/long (Geodetic alias)<br>#<br># +init=epsg:4269 +proj=longlat +datum=NAD83 +no_defs +ellps=GRS80<br># +towgs84=0,0,0<br># ---- To Coordinate System ----<br>#Lambert Conformal Conic<br># Conic, Sph&Ell<br># lat_1= and lat_2= or lat_0<br># +init=epsg:2285 +proj=lcc +lat_1=48.73333333333333 +lat_2=47.5 +lat_0=47<br># +lon_0=-120.8333333333333 +x_0=500000.0001016001 +y_0=0 +datum=NAD83<br># +units=us-ft +no_defs +ellps=GRS80 +towgs84=0,0,0<br>-118.5293900000000300 48.7408309999860520<br>2196293.3184067495000000 <wbr> 643350.3930111383100000 0.0000000000000000<br>-118.5293900000000300 48.7408309999721180<br>2196293.3184069018000000 <wbr> 643350.3930060574800000 0.0000000000000000<br>-118.5293900000000300 48.7408309999581850<br>2196293.3184070541000000 <wbr> 643350.3930009742000000 0.0000000000000000<br>-118.5293900000000300 48.7408309999442440<br>2196293.3184072063000000 <wbr> 643350.3929958911600000 0.0000000000000000<br> -118.5293900000000300 48.7408309999302960<br>2196293.3184073586000000 <wbr> 643350.3929908055600000 0.0000000000000000<br>-118.5293900000000300 48.7408309999163550<br>2196293.3184075109000000 <wbr> 643350.3929857177400000 0.0000000000000000<br>-118.5293900000000300 48.7408309999023930<br>2196293.3184076636000000 <wbr> 643350.3929806276000000 0.0000000000000000</span></font><br></span></p><p class="MsoNormal"><span lang="EN-US"><br></span></p>
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">Thanks,</span></p>
<p style="margin-bottom:0.0001pt" class="MsoNormal"><span lang="EN-US">-Dmitry Mefed</span></p></div>
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