tag:blogger.com,1999:blog-1675184707067447729.post2854384582057965736..comments2023-07-12T07:12:04.697-07:00Comments on The RAS Solution: Extra Precision in Interpolated Cross SectionsChris G.http://www.blogger.com/profile/00354834185663924786noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-1675184707067447729.post-2795272290364517542015-10-27T07:37:20.973-07:002015-10-27T07:37:20.973-07:00The rounding options for terrain development that ...The rounding options for terrain development that are base 2 (1/16, 1/32, 1/128, etc) are just another way of defining the precision in addition to the conventional base 10 options (1/10, 1/00, 1/1000, etc.). 1/10 means you are rounding to the nearest 0.1 meter (or foot). 1/16 means you are rounding to the nearest 0.0625 meter (or foot). Base 2 options are included because they are actually more computationally efficient than base 10 options. Many times you'll find 1/16 goes faster and takes less storage space than 1/10, even though it has more precision.Chris G.https://www.blogger.com/profile/03272464763887890080noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-9741606941467555862015-10-25T22:40:13.415-07:002015-10-25T22:40:13.415-07:00What is the precision of HEC-RAS version 5? In HEC...What is the precision of HEC-RAS version 5? In HEC-RAS 5 we can select different elevation precisions (1/32, 1/128 ...). Do those precisions mean that 1/32 rounds to the second decimal and 1/128 rounds to the third decimal?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-1454166119212645782013-04-11T15:27:59.038-07:002013-04-11T15:27:59.038-07:00The HEC-RAS Bloggery officially discourages GIGO m...The HEC-RAS Bloggery officially discourages GIGO modeling. Chris G.https://www.blogger.com/profile/00354834185663924786noreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-26009361010756260532013-04-11T13:46:04.772-07:002013-04-11T13:46:04.772-07:00Wow, 0.000,001 computation precision? Just curiou...Wow, 0.000,001 computation precision? Just curious what the units are; miles? <br /><br />Survey shots may be recorded to the 0.01 foot but the actual ground surface will likely be +/-0.1 foot if its a mowed lawn. +/- 1.0 foot if its a relatively flat overbank area. HEC-RAS does straight line interpolation between those shots. <br /><br />A natural channel may scour and re-fill several feet as a hydrograph peaks and then recedes back to base flow.<br /><br />PLEASE, do not encourage GIGO modeling. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1675184707067447729.post-82483964164724189372011-09-16T11:03:41.888-07:002011-09-16T11:03:41.888-07:00I know this is 3 years later and I'm not sure ...I know this is 3 years later and I'm not sure if anybody would even read this but...<br /><br />In what real-world situation would 6 digits after the decimal be applicable to modeling or design?. In feet, that's one-one millionth of a foot. Most survey data is only accurate to a tenth of a foot. Plus, this example is using interpolated cross sections. Unless, there's some strange velocity changes and the cross sections are far apart they may not even be necessary. It sounds like interpolated cross sections are being placed way too close together in an area with very little grade.<br /><br />I can understand that tweaks may be necessary to stabilize the model, but this seems a little bit extreme to me. The area could just as well be modeled as flat. In fact, given the error in survey, it could technically be slightly uphill.<br /><br />The advice in this post IS a valid solution to this problem. I'm just confused on how this problem could actually present itself. Perhaps in my limited experience I'm missing something.Anonymousnoreply@blogger.com