<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<div class="moz-cite-prefix">On 11/06/2015 6:14 PM, johnw wrote:<br>
</div>
<blockquote cite="mid:25AE8C31-AC6F-4716-9603-3C7B6ABB6F80@mac.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Jun 11, 2015, at 4:49 PM, Martin Koppenhoefer
<<a moz-do-not-send="true"
href="mailto:dieterdreist@gmail.com" class="">dieterdreist@gmail.com</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class=""><span style="font-family: Helvetica; font-size:
13px; font-style: normal; font-variant: normal;
font-weight: normal; letter-spacing: normal; line-height:
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;
float: none; display: inline !important;" class="">offsets
are an approximation to reduce the inherent problems of
some aerial layers, they won't solve problems like
distortions. JOSM isn't more precise to find a "proper
offset" than any other tool, I suggest you simply move the
layer till it visually seems ok. Unless you do high
precision measurements in the field you won't know for
sure what is "right" and what is "wrong", or in other
words: more or less accurate. IMHO, relative precision (eg
alignment, angles, straight vs curves etc) is more
important than positional precision.</span><br
style="font-family: Helvetica; font-size: 13px;
font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: 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;"
class="">
</div>
</blockquote>
</div>
<br class="">
<div class=""><br class="">
</div>
<div class="">I know the precision isn’t so important, but I want
everything to be the same relative location. The relative
position is very important to me. I know distortion can skew
that, for hills and the like. </div>
<div class=""><br class="">
</div>
<div class="">I was also under the impression there was a plugin
for JSOM that offered automatic imagery offset correction,
something which I don’t have access to in iD</div>
<div class=""><br class="">
</div>
<br>
</blockquote>
<br>
I think that JOSM offset is simply from someone sending in their
offset. I don't trust it. <br>
<br>
If you want to pick an OSM node/way to align to, I'd chose one that
is close to the imagery alignment and has a tag with
source:location= gps/survey .. and preferably one that has not been
moved since that tag was added. <br>
</body>
</html>